Behat fails due to a language change

[ewallah]

Due to a language change, the Behat command fails:

001 Scenario: Images are optimised as required.                    # filter/imageopt/tests/behat/image_processing.feature:39
      And I should see "You can not enrol yourself in this course" # filter/imageopt/tests/behat/image_processing.feature:57

Behat works fine when you update the string to: "You cannot enrol yourself in this course"