This was a case of too much code. The --start-dirty option should act
  just like --start-and-exit, except it skips the database initialization
  step. Now it does, which means it picks up the options from the specified
  test case.


mysql-test/mysql-test-run.pl:
  Fix handle of --start-dirty to be like --start-and-exit, without the
  database initialization, as it was (sort of) documented.