don't try to tag unnecessarily

delojza.py

@@ -208,7 +208,13 @@ class DelojzaBot:
             filenames.append(final_filename)
 
             if audio and is_mp3:
-                self.tag_file(final_filename, message)
+                try:
+                    id3 = mutagen.id3.ID3(final_filename)
+                    untagged = 'TIT2' not in id3
+                except mutagen.id3.ID3NoHeaderError:
+                    untagged = True
+                if untagged:
+                    self.tag_file(final_filename, message)
 
         return filenames