Improved debugging.

modules/scheduling/fallback_manager.py

@@ -192,12 +192,14 @@ class FallbackManager:
         # This should save used memory if the engine runs for a long time
         if self.last_fallback < SimpleUtil.timestamp() - (60*60*24):
             self.fallback_history = {}
+            self.logger.info("Cleared fallback history.")
         self.last_fallback = SimpleUtil.timestamp()
         
         # Retrieve files which haven't been played yet
         history = set(self.fallback_history.keys())
-        left_audio_files = list(set(audio_files).difference(history))
-
+        left_audio_files = list( set(audio_files) - (history) )
+        self.logger.info("Left fallback audio-files: %d/%d" % (len(left_audio_files), len(audio_files)))
+        
         # If nothing left, clear history and start with all files again
         if not len(left_audio_files):
             self.fallback_history = {}