trx_free_prepared(): The function trx_resurrect_insert()
can resurrect a committed transaction when the TRX_UNDO_STATE
field is not TRX_UNDO_ACTIVE or TRX_UNDO_PREPARED.
(In the examined failure of mariabackup.xb_compressed_encrypted,
assertion failure in --apply-log shutdown at line 25,
the TRX_UNDO_STATE strangely contained the value 0xffff.)

In any case, the assertion must allow the state
TRX_STATE_COMMITTED_IN_MEMORY for resurrected transactions.