Resetting the master before stopping the slave was generating the message
"[ERROR] Slave I/O: Got fatal error 1236 from master when reading data from
binary log: 'could not find next log', Error_code: 1236". In consequence,
the test case was failing because the message had not been suppressed.

To circumvent the failure, we rewrote the test stopping the slave before
resetting the master. We prefer this alternative rather than suppressing
the message.