Disclaimer: This report was fixed in a previous commit with
MDEV-21117, this patch only adds a test to show the presence of
the fix.
Prior to MDEV-21117, the ordering of the handlers in a
transaction's ha_info list solely determined the order in which
the handlertons commit. The binlog is supposed to commit first,
and is normally placed first in the ha_list to do so; however,
in multi-engine 2-phase XA transactions, the binlog can be
placed second. This allowed a race-condition for other
concurrent transactions to commit and binlog before the prior
XA COMMIT would be written to binlog.
MDEV-21117 fixed this so the binlog is specially considered
to commit first, before traversing the ha_list (see
commit_one_phase_2() in sql/hander.cc for this specific change
in 6c39eaeb12).
