Fix AudioLengthTask for the case where we don't have the decoder,
by instead of doing get_state, waiting for an ASYNC_DONE or ERROR
message. Properly raise a gst.GError in that case.
* morituri/common/task.py:
Add some debug.
* morituri/test/test_image_image.py:
After this fix, we now catch the TYPE_NOT_FOUND because of an
empty stream instead of the later gst.QueryError.
* morituri/test/test_common_encode.py:
Let us know what it is if not a gst.QueryError.
8ea1dc025d