From 97b1b4f3a682377aa8f03348618e79bd1df1772e Mon Sep 17 00:00:00 2001
From: Jeff King <peff@peff.net>
Date: Fri, 25 Mar 2011 14:10:38 -0400
Subject: merge: merge unborn index before setting ref

When we merge into an unborn branch, there are basically two
steps:

  1. Write the sha1 of the new commit into the ref pointed
     to by HEAD.

  2. Update the index with the new content, and check it out
     to the working tree.

We currently do them in this order. However, (2) is the step
that is much more likely to fail, since it can be blocked by
things like untracked working tree files. When it does, the
merge fails and we are left with an empty index but an
updated HEAD.

This patch switches the order, so that a failure in updating
the index leaves us unchanged. Of course, a failure in
updating the ref now leaves us with an updated index and
mis-matched HEAD. That is arguably not much better, but it
is probably less likely to actually happen.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/merge.c b/builtin/merge.c
index aa3453c..c8d028c 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1063,9 +1063,9 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		remote_head = peel_to_type(argv[0], 0, NULL, OBJ_COMMIT);
 		if (!remote_head)
 			die("%s - not something we can merge", argv[0]);
+		read_empty(remote_head->sha1, 0);
 		update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
 				DIE_ON_ERR);
-		read_empty(remote_head->sha1, 0);
 		return 0;
 	} else {
 		struct strbuf merge_names = STRBUF_INIT;
diff --git a/t/t7607-merge-overwrite.sh b/t/t7607-merge-overwrite.sh
index c86e298..b54e840 100755
--- a/t/t7607-merge-overwrite.sh
+++ b/t/t7607-merge-overwrite.sh
@@ -157,6 +157,10 @@ test_expect_success 'will not overwrite untracked file on unborn branch' '
 	test_cmp important c0.c
 '
 
+test_expect_success 'failed merge leaves unborn branch in the womb' '
+	test_must_fail git rev-parse --verify HEAD
+'
+
 test_expect_success 'set up unborn branch and content' '
 	git symbolic-ref HEAD refs/heads/unborn &&
 	rm -f .git/index &&
-- 
cgit v0.10.2-6-g49f6


From 4b3ffe5184bd550dddacdd0b32b18ad0e73c7908 Mon Sep 17 00:00:00 2001
From: Jeff King <peff@peff.net>
Date: Fri, 25 Mar 2011 14:13:31 -0400
Subject: pull: do not clobber untracked files on initial pull

For a pull into an unborn branch, we do not use "git merge"
at all. Instead, we call read-tree directly. However, we
used the --reset parameter instead of "-m", which turns off
the safety features.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-pull.sh b/git-pull.sh
index 63b063a..e31226b 100755
--- a/git-pull.sh
+++ b/git-pull.sh
@@ -274,7 +274,7 @@ esac
 if test -z "$orig_head"
 then
 	git update-ref -m "initial pull" HEAD $merge_head "$curr_head" &&
-	git read-tree --reset -u HEAD || exit 1
+	git read-tree -m -u HEAD || exit 1
 	exit
 fi
 
diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh
index 0470a81..0e5eb67 100755
--- a/t/t5520-pull.sh
+++ b/t/t5520-pull.sh
@@ -46,6 +46,17 @@ test_expect_success 'pulling into void using master:master' '
 	test_cmp file cloned-uho/file
 '
 
+test_expect_success 'pulling into void does not overwrite untracked files' '
+	git init cloned-untracked &&
+	(
+		cd cloned-untracked &&
+		echo untracked >file &&
+		test_must_fail git pull .. master &&
+		echo untracked >expect &&
+		test_cmp expect file
+	)
+'
+
 test_expect_success 'test . as a remote' '
 
 	git branch copy master &&
-- 
cgit v0.10.2-6-g49f6