[RFC PATCH] Fix gitdir detection when in subdir of gitdir

["SZEDER Gábor" <szeder@ira.uka.de>]

If the current working directory is a subdirectory of the gitdir (e.g.
<repo>/.git/refs/), then setup_git_directory_gently() will climb its
parent directories until it finds itself in a gitdir.  However, no
matter how many parent directories it climbs, it sets
'GIT_DIR_ENVIRONMENT' to ".", which is obviously wrong.

This behaviour affected at least 'git rev-parse --git-dir' and hence
caused some errors in bash completion (e.g. customized command prompt
when on a detached head and completion of refs).

To fix this, we set the absolute path of the found gitdir instead.

Signed-off-by: SZEDER Gábor <szeder@ira.uka.de>
---

  I'm not sure about setting an absolut path instead of a relative one
  (hence the RFC), although I think it should not make any difference.
  Of course I could have count the number of chdir("..") calls and then
  construct a "../../..", but that would have been more intrusive than
  this two-liner.

 setup.c             |    3 ++-
 t/t1501-worktree.sh |    7 +++++++
 2 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/setup.c b/setup.c
index 6b277b6..b787a54 100644
--- a/setup.c
+++ b/setup.c
@@ -456,7 +456,8 @@ const char *setup_git_directory_gently(int *nongit_ok)
 			inside_git_dir = 1;
 			if (!work_tree_env)
 				inside_work_tree = 0;
-			setenv(GIT_DIR_ENVIRONMENT, ".", 1);
+			cwd[offset] = '\0';
+			setenv(GIT_DIR_ENVIRONMENT, cwd, 1);
 			check_repository_format_gently(nongit_ok);
 			return NULL;
 		}
diff --git a/t/t1501-worktree.sh b/t/t1501-worktree.sh
index f6a6f83..27dc6c5 100755
--- a/t/t1501-worktree.sh
+++ b/t/t1501-worktree.sh
@@ -92,6 +92,13 @@ cd sub/dir || exit 1
 test_rev_parse 'in repo.git/sub/dir' false true true sub/dir/
 cd ../../../.. || exit 1
 
+test_expect_success 'detecting gitdir when cwd is in a subdir of gitdir' '
+	(expected=$(pwd)/repo.git &&
+	 cd repo.git/refs &&
+	 unset GIT_DIR &&
+	 test "$expected" = "$(git rev-parse --git-dir)")
+'
+
 test_expect_success 'repo finds its work tree' '
 	(cd repo.git &&
 	 : > work/sub/dir/untracked &&
-- 
1.6.1.153.g15508