1. Add an Atom feed to the Podcasts plugin
2. Try to browse that Atom feed
3. RSS parser crashes as it doesn't know how to parse Atom

==8560== Invalid read of size 8
==8560==    at 0x1BBD36DF: parse_feed (grl-podcasts.c:1274)
==8560==    by 0x1BBD36DF: read_feed_cb (grl-podcasts.c:1365)
==8560==    by 0x1BBD1272: read_done_cb (grl-podcasts.c:494)
==8560==    by 0x52F1A69: g_simple_async_result_complete (in /usr/lib64/libgio-2.0.so.0.5800.3)
==8560==    by 0x1BB48D2F: read_async_cb (grl-net-wc.c:619)
==8560==  Address 0x10 is not stack'd, malloc'd or (recently) free'd