PlaylistFetcher: avoid repeated fetch when we run off the edge of live playlists

    const int32_t lastSeqNumberInPlaylist =

        firstSeqNumberInPlaylist + (int32_t)mPlaylist->size() - 1;

    if (mStartup && mSeqNumber >= 0

            && (mSeqNumber < firstSeqNumberInPlaylist || mSeqNumber > lastSeqNumberInPlaylist)) {

        // in case we guessed wrong during reconfiguration, try fetching the latest content.

        mSeqNumber = lastSeqNumberInPlaylist;

    }

    if (mDiscontinuitySeq < 0) {

        mDiscontinuitySeq = mPlaylist->getDiscontinuitySeq();

    }