[PATCH] Revert "setup: set env $GIT_WORK_TREE when work tree is set, like $GIT_DIR"

This commit has caused three regression reports so far. All of them are
about spawning git subprocesses, where the new presence of GIT_WORK_TREE
either changes command behaviour (git-init or git-clone), or how
repo/worktree is detected (from aliases), with or without $GIT_DIR.
The original bug will be re-fixed another way.

Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
---
 On Thu, Dec 3, 2015 at 12:09 AM, Junio C Hamano [off-list ref] wrote:
 > OK, when/if you decide that our first step should be a revert of
 > d95138e please send in a patch to do so with a brief write-up of a
 > follow-up plan.

 Three reports to me are enough. And I obviously could not push the
 fix out fast enough. So if you want to revert it, here's the patch on
 maint.

 environment.c      | 2 --
 t/t0002-gitfile.sh | 2 +-
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/environment.c b/environment.c
index 23a38e4..f1a2a49 100644
--- a/environment.c
+++ b/environment.c

@@ -238,8 +238,6 @@ void set_git_work_tree(const char *new_work_tree)
 	}
 	git_work_tree_initialized = 1;
 	work_tree = xstrdup(real_path(new_work_tree));
-	if (setenv(GIT_WORK_TREE_ENVIRONMENT, work_tree, 1))
-		die("could not set GIT_WORK_TREE to '%s'", work_tree);
 }
 
 const char *get_git_work_tree(void)

diff --git a/t/t0002-gitfile.sh b/t/t0002-gitfile.sh
index 9670e8c..3afe012 100755
--- a/t/t0002-gitfile.sh
+++ b/t/t0002-gitfile.sh

@@ -99,7 +99,7 @@ test_expect_success 'check rev-list' '
 	test "$SHA" = "$(git rev-list HEAD)"
 '
 
-test_expect_success 'setup_git_dir twice in subdir' '
+test_expect_failure 'setup_git_dir twice in subdir' '
 	git init sgd &&
 	(
 		cd sgd &&

-- 
2.3.0.rc1.137.g477eb31