make db::dir::Writer equally stubborn

Every recording it starts must be sent to the syncer with at least one sample
written. It will try forever (unless the channel is down, then panic). This
avoids the situation in which it prevents something in the uncommitted
VecDeque from ever being synced and thus any further recordings from being
flushed.

src/mp4.rs

@@ -1753,8 +1753,8 @@ mod tests {
             extra_data.width, extra_data.height, extra_data.sample_entry,
             extra_data.rfc6381_codec).unwrap();
         let dir = db.dirs_by_stream_id.get(&TEST_STREAM_ID).unwrap();
-        let mut output = dir.create_writer(&db.db, &db.syncer_channel, None,
-                                           TEST_STREAM_ID, video_sample_entry_id).unwrap();
+        let mut output = dir::Writer::new(dir, &db.db, &db.syncer_channel, TEST_STREAM_ID,
+                                          video_sample_entry_id);
 
         // end_pts is the pts of the end of the most recent frame (start + duration).
         // It's needed because dir::Writer calculates a packet's duration from its pts and the
@@ -1777,7 +1777,7 @@ mod tests {
                          pkt.is_key()).unwrap();
             end_pts = Some(pts + pkt.duration() as i64);
         }
-        output.close(end_pts).unwrap();
+        output.close(end_pts);
         db.syncer_channel.flush();
     }