This fixes a bug where streams that won't play somehow appear with the
metadata of a previously played stream.  As far as I can tell, the only
reason this is done is to sync any buffered metadata with the displayed
metadata when decoding stops, so there should be no other adverse effects.

git-svn-id: https://svn.musicpd.org/mpd/trunk@5161 09075e82-0dd4-0310-85a5-a0d7c8717e4f