Add a test for git-commit being confused by relative GIT_DIR

Signed-off-by: David Kastrup <dak@gnu.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t2050-git-dir-relative.sh

@@ -0,0 +1,55 @@
+#!/bin/sh
+
+test_description='check problems with relative GIT_DIR
+
+This test creates a working tree state with a file and subdir:
+
+  top (committed several times)
+  subdir (a subdirectory)
+
+It creates a commit-hook and tests it, then moves .git
+into the subdir while keeping the worktree location,
+and tries commits from the top and the subdir, checking
+that the commit-hook still gets called.'
+
+. ./test-lib.sh
+
+COMMIT_FILE="$(pwd)/output"
+export COMMIT_FILE
+
+test_expect_success 'Setting up post-commit hook' '
+mkdir -p .git/hooks &&
+echo >.git/hooks/post-commit "#!/bin/sh
+touch \"\${COMMIT_FILE}\"
+echo Post commit hook was called." &&
+chmod +x .git/hooks/post-commit'
+
+test_expect_success 'post-commit hook used ordinarily' '
+echo initial >top &&
+git-add top
+git-commit -m initial &&
+test -r "${COMMIT_FILE}"
+'
+
+rm -rf "${COMMIT_FILE}"
+mkdir subdir
+mv .git subdir
+
+test_expect_success 'post-commit-hook created and used from top dir' '
+echo changed >top &&
+git --git-dir subdir/.git add top &&
+git --git-dir subdir/.git commit -m topcommit &&
+test -r "${COMMIT_FILE}"
+'
+
+rm -rf "${COMMIT_FILE}"
+
+test_expect_success 'post-commit-hook from sub dir' '
+echo changed again >top
+cd subdir &&
+git --git-dir .git --work-tree .. add ../top &&
+git --git-dir .git --work-tree .. commit -m subcommit &&
+test -r "${COMMIT_FILE}"
+'
+
+test_done