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2015-08-05builtin-am: implement -i/--interactivePaul Tan
Since d1c5f2a (Add git-am, applymbox replacement., 2005-10-07), git-am.sh supported the --interactive mode. After parsing the patch mail and extracting the patch, commit message and authorship info, an interactive session will begin that allows the user to choose between: * applying the patch * applying the patch and all subsequent patches (by disabling interactive mode in subsequent patches) * skipping the patch * editing the commit message Since f89ad67 (Add [v]iew patch in git-am interactive., 2005-10-25), git-am.sh --interactive also supported viewing the patch to be applied. When --resolved-ing in --interactive mode, we need to take care to update the patch with the contents of the index, such that the correct patch will be displayed when the patch is viewed in interactive mode. Re-implement the above in builtin/am.c Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: support and auto-detect mercurial patchesPaul Tan
Since 0cfd112 (am: preliminary support for hg patches, 2011-08-29), git-am.sh could convert mercurial patches to an RFC2822 mail patch suitable for parsing with git-mailinfo, and queue them in the state directory for application. Since 15ced75 (git-am foreign patch support: autodetect some patch formats, 2009-05-27), git-am.sh was able to auto-detect mercurial patches by checking if the file begins with the line: # HG changeset patch Re-implement the above in builtin/am.c. Helped-by: Stefan Beller <sbeller@google.com> Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: support and auto-detect StGit series filesPaul Tan
Since c574e68 (git-am foreign patch support: StGIT support, 2009-05-27), git-am.sh is able to read a single StGit series file and, for each StGit patch listed in the file, convert the StGit patch into a RFC2822 mail patch suitable for parsing with git-mailinfo, and queue them in the state directory for applying. Since 15ced75 (git-am foreign patch support: autodetect some patch formats, 2009-05-27), git-am.sh is able to auto-detect StGit series files by checking to see if the file starts with the string: # This series applies on GIT commit Re-implement the above in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: support and auto-detect StGit patchesPaul Tan
Since c574e68 (git-am foreign patch support: StGIT support, 2009-05-27), git-am.sh supported converting StGit patches into RFC2822 mail patches that can be parsed with git-mailinfo. Implement this by introducing two functions in builtin/am.c: stgit_patch_to_mail() and split_mail_conv(). stgit_patch_to_mail() is a callback function for split_mail_conv(), and contains the logic for converting an StGit patch into an RFC2822 mail patch. split_mail_conv() implements the logic to go through each file in the `paths` list, reading from stdin where specified, and calls the callback function to write the converted patch to the corresponding output file in the state directory. This interface should be generic enough to support other foreign patch formats in the future. Since 15ced75 (git-am foreign patch support: autodetect some patch formats, 2009-05-27), git-am.sh is able to auto-detect StGit patches. Re-implement this in builtin/am.c. Helped-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: rerere supportPaul Tan
git-am.sh will call git-rerere at the following events: * "git rerere" when a three-way merge fails to record the conflicted automerge results. Since 8389b52 (git-rerere: reuse recorded resolve., 2006-01-28) * Since cb6020b (Teach --[no-]rerere-autoupdate option to merge, revert and friends, 2009-12-04), git-am.sh supports the --[no-]rerere-autoupdate option as well, and would pass it to git-rerere. * "git rerere" when --resolved, to record the hand resolution. Since f131dd4 (rerere: record (or avoid misrecording) resolved, skipped or aborted rebase/am, 2006-12-08) * "git rerere clear" when --skip-ing. Since f131dd4 (rerere: record (or avoid misrecording) resolved, skipped or aborted rebase/am, 2006-12-08) * "git rerere clear" when --abort-ing. Since 3e5057a (git am --abort, 2008-07-16) Re-implement the above in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: invoke post-applypatch hookPaul Tan
Since d1c5f2a (Add git-am, applymbox replacement., 2005-10-07), git-am.sh will invoke the post-applypatch hook after the patch is applied and a commit is made. The exit code of the hook is ignored. Re-implement this in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: invoke pre-applypatch hookPaul Tan
Since d1c5f2a (Add git-am, applymbox replacement., 2005-10-07), git-am.sg will invoke the pre-applypatch hook after applying the patch to the index, but before a commit is made. Should the hook exit with a non-zero status, git am will exit. Re-implement this in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: invoke applypatch-msg hookPaul Tan
Since d1c5f2a (Add git-am, applymbox replacement., 2005-10-07), git-am.sh will invoke the applypatch-msg hooks just after extracting the patch message. If the applypatch-msg hook exits with a non-zero status, git-am.sh abort before even applying the patch to the index. Re-implement this in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: support automatic notes copyingPaul Tan
Since eb2151b (rebase: support automatic notes copying, 2010-03-12), git-am.sh supported automatic notes copying in --rebasing mode by invoking "git notes copy" once it has finished applying all the patches. Re-implement this feature in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: invoke post-rewrite hookPaul Tan
Since 96e1948 (rebase: invoke post-rewrite hook, 2010-03-12), git-am.sh will invoke the post-rewrite hook after it successfully finishes applying all the queued patches. To do this, when parsing a mail to extract its patch and metadata, in --rebasing mode git-am.sh will also store the original commit ID in the $state_dir/original-commit file. Once it applies and commits the patch, the original commit ID, and the new commit ID, will be appended to the $state_dir/rewritten file. Once all of the queued mail have been processed, git-am.sh will then invoke the post-rewrite hook with the contents of the $state_dir/rewritten file. Re-implement this in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement -S/--gpg-sign, commit.gpgsignPaul Tan
Since 3b4e395 (am: add the --gpg-sign option, 2014-02-01), git-am.sh supported the --gpg-sign option, and would pass it to git-commit-tree, thus GPG-signing the commit object. Re-implement this option in builtin/am.c. git-commit-tree would also sign the commit by default if the commit.gpgsign setting is true. Since we do not run commit-tree, we re-implement this behavior by handling the commit.gpgsign setting ourselves. Helped-by: Stefan Beller <sbeller@google.com> Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement --committer-date-is-author-datePaul Tan
Since 3f01ad6 (am: Add --committer-date-is-author-date option, 2009-01-22), git-am.sh implemented the --committer-date-is-author-date option, which tells git-am to use the timestamp recorded in the email message as both author and committer date. Re-implement this option in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement --ignore-datePaul Tan
Since a79ec62 (git-am: Add --ignore-date option, 2009-01-24), git-am.sh supported the --ignore-date option, and would use the current timestamp instead of the one provided in the patch if the option was set. Re-implement this option in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: pass git-apply's options to git-applyPaul Tan
git-am.sh recognizes some of git-apply's options, and would pass them to git-apply: * --whitespace, since 8c31cb8 (git-am: --whitespace=x option., 2006-02-28) * -C, since 67dad68 (add -C[NUM] to git-am, 2007-02-08) * -p, since 2092a1f (Teach git-am to pass -p option down to git-apply, 2007-02-11) * --directory, since b47dfe9 (git-am: add --directory=<dir> option, 2009-01-11) * --reject, since b80da42 (git-am: implement --reject option passed to git-apply, 2009-01-23) * --ignore-space-change, --ignore-whitespace, since 86c91f9 (git apply: option to ignore whitespace differences, 2009-08-04) * --exclude, since 77e9e49 (am: pass exclude down to apply, 2011-08-03) * --include, since 58725ef (am: support --include option, 2012-03-28) * --reject, since b80da42 (git-am: implement --reject option passed to git-apply, 2009-01-23) Re-implement support for these options in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement --[no-]scissorsPaul Tan
Since 017678b (am/mailinfo: Disable scissors processing by default, 2009-08-26), git-am supported the --[no-]scissors option, passing it to git-mailinfo. Re-implement support for this option in builtin/am.c. Since the default setting of --scissors in git-mailinfo can be configured with mailinfo.scissors (and perhaps through other settings in the future), to be safe we make an explicit distinction between SCISSORS_UNSET, SCISSORS_TRUE and SCISSORS_FALSE. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: support --keep-cr, am.keepcrPaul Tan
Since ad2c928 (git-am: Add command line parameter `--keep-cr` passing it to git-mailsplit, 2010-02-27), git-am.sh supported the --keep-cr option and would pass it to git-mailsplit. Since e80d4cb (git-am: Add am.keepcr and --no-keep-cr to override it, 2010-02-27), git-am.sh supported the am.keepcr config setting, which controls whether --keep-cr is on by default. Re-implement the above in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement --[no-]message-id, am.messageidPaul Tan
Since a078f73 (git-am: add --message-id/--no-message-id, 2014-11-25), git-am.sh supported the --[no-]message-id options, and the "am.messageid" setting which specifies the default option. --[no-]message-id tells git-am whether or not the -m option should be passed to git-mailinfo. Re-implement this option in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement -k/--keep, --keep-non-patchPaul Tan
Since d1c5f2a (Add git-am, applymbox replacement., 2005-10-07), git-am.sh supported the -k/--keep option to pass the -k option to git-mailsplit. Since f7e5ea1 (am: learn passing -b to mailinfo, 2012-01-16), git-am.sh supported the --keep-non-patch option to pass the -b option to git-mailsplit. Re-implement these two options in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement -u/--utf8Paul Tan
Since d1c5f2a (Add git-am, applymbox replacement., 2005-10-07), git-am.sh supported the -u,--utf8 option. If set, the -u option will be passed to git-mailinfo to re-code the commit log message and authorship in the charset specified by i18n.commitencoding. If unset, the -n option will be passed to git-mailinfo, which disables the re-encoding. Since d84029b (--utf8 is now default for 'git-am', 2007-01-08), --utf8 is specified by default in git-am.sh. Re-implement the above in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: handle stray state directoryPaul Tan
Should git-am terminate unexpectedly between the point where the state directory is created, but the "next" and "last" files are not written yet, a stray state directory will be left behind. As such, since b141f3c (am: handle stray $dotest directory, 2013-06-15), git-am.sh explicitly recognizes such a stray directory, and allows the user to remove it with am --abort. Re-implement this feature in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: bypass git-mailinfo when --rebasingPaul Tan
Since 5e835ca (rebase: do not munge commit log message, 2008-04-16), git am --rebasing no longer gets the commit log message from the patch, but reads it directly from the commit identified by the "From " header line. Since 43c2325 (am: use get_author_ident_from_commit instead of mailinfo when rebasing, 2010-06-16), git am --rebasing also gets the author name, email and date directly from the commit. Since 0fbb95d (am: don't call mailinfo if $rebasing, 2012-06-26), git am --rebasing does not use git-mailinfo to get the patch body, but rather generates it directly from the commit itself. The above 3 commits introduced a separate parse_mail() code path in git-am.sh's --rebasing mode that bypasses git-mailinfo. Re-implement this code path in builtin/am.c as parse_mail_rebase(). Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement --rebasing modePaul Tan
Since 3041c32 (am: --rebasing, 2008-03-04), git-am.sh supported the --rebasing option, which is used internally by git-rebase to tell git-am that it is being used for its purpose. It would create the empty file $state_dir/rebasing to help "completion" scripts tell if the ongoing operation is am or rebase. As of 0fbb95d (am: don't call mailinfo if $rebasing, 2012-06-26), --rebasing also implies --3way as well. Since a1549e1 (am: return control to caller, for housekeeping, 2013-05-12), git-am.sh would only clean up the state directory when it is not --rebasing, instead deferring cleanup to git-rebase.sh. Re-implement the above in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement --3wayPaul Tan
Since d1c5f2a (Add git-am, applymbox replacement., 2005-10-07), git-am.sh supported the --3way option, and if set, would attempt to do a 3-way merge if the initial patch application fails. Since 5d86861 (am -3: list the paths that needed 3-way fallback, 2012-03-28), in a 3-way merge git-am.sh would list the paths that needed 3-way fallback, so that the user can review them more carefully to spot mismerges. Re-implement the above in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement -s/--signoffPaul Tan
Since d1c5f2a (Add git-am, applymbox replacement., 2005-10-07), git-am supported the --signoff option which will append a signoff at the end of the commit messsage. Re-implement this feature in parse_mail() by calling append_signoff() if the option is set. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: exit with user friendly message on failurePaul Tan
Since ced9456 (Give the user a hint for how to continue in the case that git-am fails because it requires user intervention, 2006-05-02), git-am prints additional information on how the user can re-invoke git-am to resume patch application after resolving the failure. Re-implement this through the die_user_resolve() function. Since cc12005 (Make git rebase interactive help match documentation., 2006-05-13), git-am supports the --resolvemsg option which is used by git-rebase to override the message printed out when git-am fails. Re-implement this option. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement -q/--quietPaul Tan
Since 0e987a1 (am, rebase: teach quiet option, 2009-06-16), git-am supported the --quiet option, and when told to be quiet, would only speak on failure. Re-implement this by introducing the say() function, which works like fprintf_ln(), but would only write to the stream when state->quiet is false. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: reject patches when there's a session in progressPaul Tan
Since d1c5f2a (Add git-am, applymbox replacement., 2005-10-07), git-am would error out if the user gave it mbox(s) on the command-line, but there was a session in progress. Since c95b138 (Fix git-am safety checks, 2006-09-15), git-am would detect if the user attempted to feed it a mbox via stdin, by checking if stdin is not a tty and there is no resume command given. Re-implement the above two safety checks. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement --abortPaul Tan
Since 3e5057a (git am --abort, 2008-07-16), git-am supported the --abort option that will rewind HEAD back to the original commit. Re-implement this through am_abort(). Since 7b3b7e3 (am --abort: keep unrelated commits since the last failure and warn, 2010-12-21), to prevent commits made since the last failure from being lost, git-am will not rewind HEAD back to the original commit if HEAD moved since the last failure. Re-implement this through safe_to_abort(). Helped-by: Stefan Beller <sbeller@google.com> Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement --skipPaul Tan
Since d1c5f2a (Add git-am, applymbox replacement., 2005-10-07), git-am supported resuming from a failed patch application by skipping the current patch. Re-implement this feature by introducing am_skip(). Helped-by: Stefan Beller <sbeller@google.com> Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: don't parse mail when resumingPaul Tan
Since 271440e (git-am: make it easier after fixing up an unapplicable patch., 2005-10-25), when "git am" is run again after being paused, the current mail message will not be re-parsed, but instead the contents of the state directory's patch, msg and author-script files will be used as-is instead. Re-implement this in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement --resolved/--continuePaul Tan
Since 0c15cc9 (git-am: --resolved., 2005-11-16), git-am supported resuming from a failed patch application. The user will manually apply the patch, and the run git am --resolved which will then commit the resulting index. Re-implement this feature by introducing am_resolve(). Since it makes no sense for the user to run am --resolved when there is no session in progress, we error out in this case. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: refuse to apply patches if index is dirtyPaul Tan
Since d1c5f2a (Add git-am, applymbox replacement., 2005-10-07), git-am will refuse to apply patches if the index is dirty. Re-implement this behavior in builtin/am.c. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement committing applied patchPaul Tan
Implement do_commit(), which commits the index which contains the results of applying the patch, along with the extracted commit message and authorship information. Since 29b6754 (am: remove rebase-apply directory before gc, 2010-02-22), git gc --auto is also invoked to pack the loose objects that are created from making the commits. Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: apply patch with git-applyPaul Tan
Implement applying the patch to the index using git-apply. If a file is unchanged but stat-dirty, git-apply may erroneously fail to apply patches, thinking that they conflict with a dirty working tree. As such, since 2a6f08a (am: refresh the index at start and --resolved, 2011-08-15), git-am will refresh the index before applying patches. Re-implement this behavior. Helped-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: extract patch and commit info with git-mailinfoPaul Tan
For the purpose of applying the patch and committing the results, implement extracting the patch data, commit message and authorship from an e-mail message using git-mailinfo. git-mailinfo is run as a separate process, but ideally in the future, we should be be able to access its functionality directly without spawning a new process. Helped-by: Junio C Hamano <gitster@pobox.com> Helped-by: Jeff King <peff@peff.net> Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: auto-detect mbox patchesPaul Tan
Since 15ced75 (git-am foreign patch support: autodetect some patch formats, 2009-05-27), git-am.sh is able to autodetect mbox, stgit and mercurial patches through heuristics. Re-implement support for autodetecting mbox/maildir files in builtin/am.c. RFC 2822 requires that lines are terminated by "\r\n". To support this, implement strbuf_getline_crlf(), which will remove both '\n' and "\r\n" from the end of the line. Helped-by: Junio C Hamano <gitster@pobox.com> Helped-by: Eric Sunshine <sunshine@sunshineco.com> Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: split out mbox/maildir patches with git-mailsplitPaul Tan
git-am.sh supports mbox, stgit and mercurial patches. Re-implement support for splitting out mbox/maildirs using git-mailsplit, while also implementing the framework required to support other patch formats in the future. Re-implement support for the --patch-format option (since a5a6755 (git-am foreign patch support: introduce patch_format, 2009-05-27)) to allow the user to choose between the different patch formats. Helped-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement patch queue mechanismPaul Tan
git-am applies a series of patches. If the process terminates abnormally, we want to be able to resume applying the series of patches. This requires the session state to be saved in a persistent location. Implement the mechanism of a "patch queue", represented by 2 integers -- the index of the current patch we are applying and the index of the last patch, as well as its lifecycle through the following functions: * am_setup(), which will set up the state directory $GIT_DIR/rebase-apply. As such, even if the process exits abnormally, the last-known state will still persist. * am_load(), which is called if there is an am session in progress, to load the last known state from the state directory so we can resume applying patches. * am_run(), which will do the actual patch application. After applying a patch, it calls am_next() to increment the current patch index. The logic for applying and committing a patch is not implemented yet. * am_destroy(), which is finally called when we successfully applied all the patches in the queue, to clean up by removing the state directory and its contents. Helped-by: Junio C Hamano <gitster@pobox.com> Helped-by: Stefan Beller <sbeller@google.com> Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-05builtin-am: implement skeletal builtin amPaul Tan
For the purpose of rewriting git-am.sh into a C builtin, implement a skeletal builtin/am.c that redirects to $GIT_EXEC_PATH/git-am if the environment variable _GIT_USE_BUILTIN_AM is not defined. Since in the Makefile git-am.sh takes precedence over builtin/am.c, $GIT_EXEC_PATH/git-am will contain the shell script git-am.sh, and thus this allows us to fall back on the functional git-am.sh when running the test suite for tests that depend on a working git-am implementation. Since git-am.sh cannot handle any environment modifications by setup_git_directory(), "am" is declared with no setup flags in git.c. On the other hand, to re-implement git-am.sh in builtin/am.c, we need to run all the git dir and work tree setup logic that git.c typically does for us. As such, we work around this temporarily by copying the logic in git.c's run_builtin(), which is roughly: prefix = setup_git_directory(); trace_repo_setup(prefix); setup_work_tree(); This redirection should be removed when all the features of git-am.sh have been re-implemented in builtin/am.c. Helped-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Paul Tan <pyokagan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>