Teach diff --submodule and status to handle .git files in submodules

The simple test for an existing .git directory gives an incorrect result
if .git is a file that records "gitdir: overthere". So for submodules that
use a .git file, "git status" and the diff family - when the "--submodule"
option is given - did assume the submodule was not populated at all when
a .git file was used, thus generating wrong output or no output at all.

This is fixed by using read_gitfile_gently() to get the correct location
of the .git directory. While at it, is_submodule_modified() was cleaned up
to use the "dir" member of "struct child_process" instead of setting the
GIT_WORK_TREE and GIT_DIR environment variables.

Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/t/t7506-status-submodule.sh b/t/t7506-status-submodule.sh
index aeec1f6..3d4f85d 100755
--- a/t/t7506-status-submodule.sh
+++ b/t/t7506-status-submodule.sh
@@ -157,6 +157,22 @@ test_expect_success 'status with added and untracked file in modified submodule
 	EOF
 '
 
+test_expect_success 'setup .git file for sub' '
+	(cd sub &&
+	 rm -f new-file
+	 REAL="$(pwd)/../.real" &&
+	 mv .git "$REAL"
+	 echo "gitdir: $REAL" >.git) &&
+	 echo .real >>.gitignore &&
+	 git commit -m "added .real to .gitignore" .gitignore
+'
+
+test_expect_success 'status with added file in modified submodule with .git file' '
+	(cd sub && git reset --hard && echo >foo && git add foo) &&
+	git status >output &&
+	grep "modified:   sub (new commits, modified content)" output
+'
+
 test_expect_success 'rm submodule contents' '
 	rm -rf sub/* sub/.git
 '