refs: move head_ref{,_submodule} to the common code

These don't use any backend-specific functions.  These were previously
defined in terms of the do_head_ref helper function, but since they
are otherwise identical, we don't need that function.

Signed-off-by: David Turner <dturner@twopensource.com>
Reviewed-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

refs.c

@@ -1080,3 +1080,26 @@ int rename_ref_available(const char *oldname, const char *newname)
 	strbuf_release(&err);
 	return ret;
 }
+
+int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
+{
+	struct object_id oid;
+	int flag;
+
+	if (submodule) {
+		if (resolve_gitlink_ref(submodule, "HEAD", oid.hash) == 0)
+			return fn("HEAD", &oid, 0, cb_data);
+
+		return 0;
+	}
+
+	if (!read_ref_full("HEAD", RESOLVE_REF_READING, oid.hash, &flag))
+		return fn("HEAD", &oid, flag, cb_data);
+
+	return 0;
+}
+
+int head_ref(each_ref_fn fn, void *cb_data)
+{
+	return head_ref_submodule(NULL, fn, cb_data);
+}

refs/files-backend.c

@@ -1745,34 +1745,6 @@ static int do_for_each_ref(struct ref_cache *refs, const char *base,
 	return do_for_each_entry(refs, base, do_one_ref, &data);
 }
 
-static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
-{
-	struct object_id oid;
-	int flag;
-
-	if (submodule) {
-		if (resolve_gitlink_ref(submodule, "HEAD", oid.hash) == 0)
-			return fn("HEAD", &oid, 0, cb_data);
-
-		return 0;
-	}
-
-	if (!read_ref_full("HEAD", RESOLVE_REF_READING, oid.hash, &flag))
-		return fn("HEAD", &oid, flag, cb_data);
-
-	return 0;
-}
-
-int head_ref(each_ref_fn fn, void *cb_data)
-{
-	return do_head_ref(NULL, fn, cb_data);
-}
-
-int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
-{
-	return do_head_ref(submodule, fn, cb_data);
-}
-
 int for_each_ref(each_ref_fn fn, void *cb_data)
 {
 	return do_for_each_ref(&ref_cache, "", fn, 0, 0, cb_data);