files-backend: delete dead code in files_init_db()

safe_create_dir() can do adjust_shared_perm() internally, and init-db
has always created 'refs' in shared mode since the beginning,
af6e277c5e (git-init-db: initialize shared repositories with --shared -
2005-12-22). So this code looks like extra adjust_shared_perm calls are
unnecessary.

And they are. But let's see why there are here in the first place.

This code was added in 6fb5acfd8f (refs: add methods to init refs db -
2016-09-04). From the diff alone this looks like a faithful refactored
code from init-db.c. But there is a subtle difference:

Between the safe_create_dir() block and adjust_shared_perm() block in
the old init-db.c, we may copy/recreate directories from the repo
template. So it makes sense that adjust_shared_perm() is re-executed
then to fix potential permission screwups.

After 6fb5acfd8f, refs dirs are created after template is copied. Nobody
will change directory permission again. So the extra adjust_shared_perm()
is redudant. Delete them.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

refs/files-backend.c

@@ -4107,10 +4107,6 @@ static int files_init_db(struct ref_store *ref_store, struct strbuf *err)
 	 */
 	safe_create_dir(git_path("refs/heads"), 1);
 	safe_create_dir(git_path("refs/tags"), 1);
-	if (get_shared_repository()) {
-		adjust_shared_perm(git_path("refs/heads"));
-		adjust_shared_perm(git_path("refs/tags"));
-	}
 	return 0;
 }