Revert "audio: be more tolerant of gstreamer states and order. Fix mo…

…pidy#1453"

This reverts commit ec52aeb.

mopidy/audio/scan.py

@@ -134,10 +134,6 @@ def _start_pipeline(pipeline):
     result = pipeline.set_state(Gst.State.PAUSED)
     if result == Gst.StateChangeReturn.NO_PREROLL:
         pipeline.set_state(Gst.State.PLAYING)
-    elif result == Gst.StateChangeReturn.ASYNC:
-        # TODO: should probably have error check here like
-        # https://cgit.freedesktop.org/gstreamer/gstreamer/tree/tools/gst-launch.c#n1075 ??
-        pipeline.set_state(Gst.State.PLAYING)
 
 
 def _query_duration(pipeline, timeout=100):
@@ -214,7 +210,7 @@ def _process(pipeline, timeout_ms):
         elif message.type == Gst.MessageType.EOS:
             return tags, mime, have_audio
         elif message.type == Gst.MessageType.ASYNC_DONE:
-            if message.src == pipeline and tags:
+            if message.src == pipeline:
                 return tags, mime, have_audio
         elif message.type == Gst.MessageType.TAG:
             taglist = message.parse_tag()