enter_repo: allow .git files in strict mode

Strict mode is about not guessing where .git is. If the user points to a
.git file, we know exactly where the target .git dir will be. This makes
it possible to serve .git files as repository on the server side.

This may be needed even in local clone case because transport.c code
uses upload-pack for fetching remote refs. But right now the
clone/transport code goes with non-strict.

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

path.c

@@ -438,8 +438,13 @@ const char *enter_repo(const char *path, int strict)
 			return NULL;
 		path = validated_path;
 	}
-	else if (chdir(path))
-		return NULL;
+	else {
+		const char *gitfile = read_gitfile(path);
+		if (gitfile)
+			path = gitfile;
+		if (chdir(path))
+			return NULL;
+	}
 
 	if (is_git_directory(".")) {
 		set_git_dir(".");

t/t0002-gitfile.sh

@@ -148,4 +148,14 @@ test_expect_success 'enter_repo linked checkout' '
 	test_cmp expected actual
 '
 
+test_expect_success 'enter_repo strict mode' '
+	git ls-remote --upload-pack="git upload-pack --strict" foo/.git >actual &&
+	cat >expected <<-\EOF &&
+	946e985ab20de757ca5b872b16d64e92ff3803a9	HEAD
+	946e985ab20de757ca5b872b16d64e92ff3803a9	refs/heads/master
+	946e985ab20de757ca5b872b16d64e92ff3803a9	refs/tags/foo
+	EOF
+	test_cmp expected actual
+'
+
 test_done