'Pre-parse the command line to extract the value of the --testrunner
option. This allows a test runner to define additional command line
arguments.'

def run_from_argv(self, argv):

    option = '--testrunner='
    for arg in argv[2:]:
        if arg.startswith(option):
            self.test_runner = arg[len(option):]
            break
    super().run_from_argv(argv)
