song: don't check song_is_file() in song_file_update()

src/song.c

@@ -100,28 +100,27 @@ song_free(struct song *song)
 int
 song_file_update(struct song *song)
 {
-	if (song_is_file(song)) {
 	struct decoder_plugin *plugin;
 	unsigned int next = 0;
 	char path_max_tmp[MPD_PATH_MAX];
 	char abs_path[MPD_PATH_MAX];
 
+	assert(song_is_file(song));
+
 	utf8_to_fs_charset(abs_path, song_get_url(song, path_max_tmp));
 	rmp2amp_r(abs_path, abs_path);
 
-		if (song->tag)
+	if (song->tag != NULL) {
 		tag_free(song->tag);
-
 		song->tag = NULL;
+	}
 
-		while (!song->tag && (plugin = isMusic(abs_path,
-						       &(song->mtime),
-						       next++))) {
+	while (song->tag == NULL &&
+	       (plugin = isMusic(abs_path, &(song->mtime), next++)))
 		song->tag = plugin->tag_dup(abs_path);
-		}
-		if (!song->tag || song->tag->time < 0)
+
+	if (song->tag == NULL || song->tag->time < 0)
 		return -1;
-	}
 
 	return 0;
 }