When InnoDB has completed the rollback of a recovered transaction,
it used to display the transaction identifier.
This was broken in MySQL 5.7.2 in
2f5f3cd3ac
which was merged to MariaDB 10.2.2 in
commit 2e814d4702.
trx_rollback_active(): Cache the transaction ID before it will be
reset by transaction commit. Do not display the message if the
rollback was interrupted by shutdown (MDEV-13797, MDEV-12352).
Sometimes, the test would fail with a result difference for
the READ UNCOMMITTED read, because the incremental backup
would finish before redo log was written for all the rows
that were inserted in the second batch.
To fix that, cause a redo log write by creating another
transaction. The transaction rollback (which internally does commit)
will be flushed to the redo log, and before that, all the preceding
changes will be flushed to the redo log as well.
Skip rollback and other redo-log-generating tasks if
srv_apply_log_only is set.
Instead of assigning the debug variable recv_no_log_write = FALSE,
assign it to srv_apply_log_only, so that any unwanted writes are caught.
