docs: def _run_validate(self):
          '''
          Execute the validate() method in the test script belonging to this job.
          '''
          assert(os.path.exists(self.validator_script_name))
          old_path = sys.path
          sys.path = [self.working_dir] + old_path
          # logger.debug('Python search path is now {0}.'.format(sys.path))
  
          try:
              module = importlib.import_module(self._validator_import_name)
          except Exception as e:
              text_student = "Internal validation problem, please contact your course responsible."
              text_tutor = "Exception while loading the validator: " + str(e)
              self._send_result(text_student, text_tutor, UNSPECIFIC_ERROR)
              return
  
          # Looped validator loading in the test suite demands this
          importlib.reload(module)
  
          # make the call
          try:
              module.validate(self)
          except Exception as e:
              # get more info
              text_student = None
              text_tutor = None
              if type(e) is TerminationException:
                  text_student = "The execution of '{0}' terminated unexpectely.".format(
                      e.instance.name)
                  text_tutor = "The execution of '{0}' terminated unexpectely.".format(
                      e.instance.name)
                  text_student += "\n\nOutput so far:\n" + e.output
                  text_tutor += "\n\nOutput so far:\n" + e.output
              elif type(e) is TimeoutException:
                  text_student = "The execution of '{0}' was cancelled, since it took too long.".format(
                      e.instance.name)
                  text_tutor = "The execution of '{0}' was cancelled due to timeout.".format(
                      e.instance.name)
                  text_student += "\n\nOutput so far:\n" + e.output
                  text_tutor += "\n\nOutput so far:\n" + e.output
              elif type(e) is NestedException:
                  text_student = "Unexpected problem during the execution of '{0}'. {1}".format(
                      e.instance.name,
                      str(e.real_exception))
                  text_tutor = "Unkown exception during the execution of '{0}'. {1}".format(
                      e.instance.name,
                      str(e.real_exception))
                  text_student += "\n\nOutput so far:\n" + e.output
                  text_tutor += "\n\nOutput so far:\n" + e.output
              elif type(e) is WrongExitStatusException:
                  text_student = "The execution of '{0}' resulted in the unexpected exit status {1}.".format(
                      e.instance.name,
                      e.got)
                  text_tutor = "The execution of '{0}' resulted in the unexpected exit status {1}.".format(
                      e.instance.name,
                      e.got)
                  text_student += "\n\nOutput so far:\n" + e.output
                  text_tutor += "\n\nOutput so far:\n" + e.output
              elif type(e) is JobException:
                  # Some problem with our own code
                  text_student = e.info_student
                  text_tutor = e.info_tutor
              elif type(e) is FileNotFoundError:
                  text_student = "A file is missing: {0}".format(
                      str(e))
                  text_tutor = "Missing file: {0}".format(
                      str(e))
              elif type(e) is AssertionError:
                  # Need this harsh approach to kill the
                  # test suite execution at this point
                  # Otherwise, the problem gets lost in
                  # the log storm
                  logger.error(
                      "Failed assertion in validation script. Should not happen in production.")
                  exit(-1)
              else:
                  # Something really unexpected
                  text_student = "Internal problem while validating your submission. Please contact the course responsible."
                  text_tutor = "Unknown exception while running the validator: {0}".format(
                      str(e))
              # We got the text. Report the problem.
              self._send_result(text_student, text_tutor, UNSPECIFIC_ERROR)
              return
          # no unhandled exception during the execution of the validator
          if not self.result_sent:
              logger.debug("Validation script forgot result sending, assuming success.")
              self.send_pass_result()
          # roll back
          sys.path = old_path
          # Test script was executed, result was somehow sent
          # Clean the file system, since we can't do anything else
          remove_working_directory(self.working_dir, self._config)