[PATCH 25/43] worktree setup: call set_git_dir explicitly

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

Currently setup_git_env() can automatically set git directory to
".git", relative to current working directory, no matter where it
is. Any access to repository may call setup_git_env() automatically if
there is no repository found yet. This leads to obscure faults where
we don't expect a repository setup to happen.

The ultimate goal (**) is:

 - Git repository will be searched and set up by either one of these
   functions (and no other functions):

   + setup_git_directory_gently()
   + setup_git_directory()
   + enter_repo()
   + init_db()

 - Repository setup can't be called more than once. If it is really
   needed, then un-setup the previous repo before moving on with
   another one.

 - Any attempts to access repository when it's not found/set up should
   be caught.

This patch is the first step to accomplish this goal. It ensures that
after the "setup function" (mentioned above) is called, if a
repository is found, then setup_git_env() must be called already.

The two other cases (no setup function called,
setup_git_directory_gently() called but no repo found) will be covered
by the next patches, to ensure setup_git_env() will not be triggered.

(**) This only applies to builtin commands, for now.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 setup.c |   11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/setup.c b/setup.c
index e067292..43a8609 100644
--- a/setup.c
+++ b/setup.c
@@ -350,14 +350,17 @@ static const char *setup_git_directory_gently_1(int *nongit_ok)
 				/* config may override worktree */
 				if (check_repository_format_gently(nongit_ok))
 					return NULL;
+				set_git_dir(gitdirenv);
 				return retval;
 			}
 			if (check_repository_format_gently(nongit_ok))
 				return NULL;
 			retval = get_relative_cwd(buffer, sizeof(buffer) - 1,
 					get_git_work_tree());
-			if (!retval || !*retval)
+			if (!retval || !*retval) {
+				set_git_dir(gitdirenv);
 				return NULL;
+			}
 			set_git_dir(make_absolute_path(gitdirenv));
 			if (chdir(work_tree_env) < 0)
 				die_errno ("Could not chdir to '%s'", work_tree_env);
@@ -392,8 +395,10 @@ static const char *setup_git_directory_gently_1(int *nongit_ok)
 	offset = len = strlen(cwd);
 	for (;;) {
 		gitfile_dir = read_gitfile_gently(DEFAULT_GIT_DIR_ENVIRONMENT);
-		if (gitfile_dir || is_git_directory(DEFAULT_GIT_DIR_ENVIRONMENT)) {
-			if (gitfile_dir && set_git_dir(gitfile_dir))
+		if (!gitfile_dir && is_git_directory(DEFAULT_GIT_DIR_ENVIRONMENT))
+			gitfile_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
+		if (gitfile_dir) {
+			if (set_git_dir(gitfile_dir))
 				die("Repository setup failed");
 			inside_git_dir = 0;
 			if (!work_tree_env)
-- 
1.7.0.rc1.541.g2da82.dirty