setup: add gentle version of resolve_git_dir

This follows a93bedada (setup: add gentle version of read_gitfile,
2015-06-09), and assumes the same reasoning. resolve_git_dir is unsuited
for speculative calls, so we want to use the gentle version to find out
about potential errors.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -509,7 +509,9 @@ extern int is_nonbare_repository_dir(struct strbuf *path);
 #define READ_GITFILE_ERR_TOO_LARGE 8
 extern const char *read_gitfile_gently(const char *path, int *return_error_code);
 #define read_gitfile(path) read_gitfile_gently((path), NULL)
-extern const char *resolve_gitdir(const char *suspect);
+extern const char *resolve_gitdir_gently(const char *suspect, int *return_error_code);
+#define resolve_gitdir(path) resolve_gitdir_gently((path), NULL)
+
 extern void set_git_work_tree(const char *tree);
 
 #define ALTERNATE_DB_ENVIRONMENT "GIT_ALTERNATE_OBJECT_DIRECTORIES"

setup.c

@@ -1017,11 +1017,11 @@ const char *setup_git_directory(void)
 	return setup_git_directory_gently(NULL);
 }
 
-const char *resolve_gitdir(const char *suspect)
+const char *resolve_gitdir_gently(const char *suspect, int *return_error_code)
 {
 	if (is_git_directory(suspect))
 		return suspect;
-	return read_gitfile(suspect);
+	return read_gitfile_gently(suspect, return_error_code);
 }
 
 /* if any standard file descriptor is missing open it to /dev/null */