The following changes are committed:

* `RESET MASTER` at the end of the test. This was necessary to allow the test
  to run on repeated runs.

* `--source include/galera_wait_ready.inc` after setting `gmcast.isolate=0` to
  get back to a primary component.

* Fix for assertion in `Protocol::end_statement()`. The assertion is due to
  the fact that function `do_command()` calls `thd->protocol->end_statement()`,
  without setting an error, when it is detected that galera is not ready yet.
  Following line somehow disappeared in a past merge:
  ```
  my_message(ER_UNKNOWN_COM_ERROR,
             "WSREP has not yet prepared node for application use", MYF(0));
  ```