storage/maria/ma_loghandler.c:
  Normally, when we log LOGREC_LONG_TRANSACTION_ID, undo_lsn should be 0: assert this.
storage/maria/ma_test_force_start.pl:
  this script does not work with mtr2, make it use mtr1
storage/maria/trnman.c:
  The bug's cause was that: transaction would log LOGREC_LONG_TRANSACTION_ID, then Checkpoint would run
  and skip it (because its undo_lsn is still 0), then transaction would log REDO+UNDO, then crash. At Recovery,
  REDO phase would start from Checkpoint's record LSN, so wouldn't see LOGREC_LONG_TRANSACTION_ID, and
  as Checkpoint record does not mention transaction, transaction would be unknown, so its REDO+UNDO would
  be thrown away (assumed to belong to a transaction committed long ago as unknown), so transaction
  would not be rolled back, which is wrong. Fix is: it was wrong to skip a transaction if undo_lsn is 0;
  as soon as LOGREC_LONG_TRANSACTION_ID has been logged, it becomes potentially invisible to the REDO
  phase, and so we must include this transaction in the checkpoint record.