Merge commit '1cac9accbd1f9b8596122d0735e37b97a844c514'

* commit '1cac9accbd1f9b8596122d0735e37b97a844c514':
  avi: properly fail if the dv demuxer is missing

Merged-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/avidec.c

@@ -522,7 +522,8 @@ static int avi_read_header(AVFormatContext *s)
                     avi->dv_demux = avpriv_dv_init_demux(s);
                     if (!avi->dv_demux)
                         goto fail;
-                }
+                } else
+                    goto fail;
                 s->streams[0]->priv_data = ast;
                 avio_skip(pb, 3 * 4);
                 ast->scale = avio_rl32(pb);