wait_until_connected_again issues 'SHOW STATUS' query repeatedly
until mysqld replies without errors.
However, SHOW STATUS is treated specially by wsrep in that it is
allowed to proceed even if wsrep is not yet in ready state. As a
consequence, after returning from wait_until_connected_again,
wsrep may not be ready yet and subsequent queries may fail with
error "1047 WSREP has not yet prepared node for application use".
To avoid those errors, the patch includes wait_wsrep_ready.inc at
the end of the wait_until_connected_again.