Under normal operation, XModules are reloaded on each request from a
student. CombinedOpenEnded modules have code that runs at initialization
that validates the students state. These changes makes that code run
during several long-form unit tests (testing CombinedOpenEnded across
multiple 'requests').

These tests are marked as expectedFailure because they now exhibit the
same failures as observed in [LMS-1493] (namely, the students state gets
reset, because CombinedOpenEnded interprets system.ajax_url raising an
error as meaning that the problem definition and the student answers are
in conflict)