/usr/lib/mysql-testsuite/t/union-master.opt is in percona-xtradb-cluster-testsuite-5.5 5.5.34-25.9+dfsg-0ubuntu4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 | --log-slow-queries --log-queries-not-using-indexes
|