Original commit message from CVS:
* ext/ogg/gstoggdemux.c: (gst_ogg_demux_src_query),
(gst_ogg_demux_src_event), (_find_chain_seek),
(gst_ogg_pad_push):
Check for pad availability before using it.
* ext/ogg/gstoggdemux.c: (_find_chain_process):
Fix parsing of chained ogg. Needs more work on the decoder side.