Merge pull request #5143 from edx/benp/solano2-bokchoy-course-outline

bok-choy: Fix flakiness in date-picker steps under studio tests

common/test/acceptance/pages/studio/overview.py

@@ -614,6 +614,7 @@ class CourseOutlineModal(object):
         for i in xrange(abs(date_diff)):
             self.page.q(css=selector).click()
         self.page.q(css="a.ui-state-default").nth(day - 1).click()  # set day
+        self.page.wait_for_element_invisibility("#ui-datepicker-div", "datepicker should be closed")
         EmptyPromise(
             lambda: getattr(self, property_name) == u'{m}/{d}/{y}'.format(m=month, d=day, y=year),
             "{} is updated in modal.".format(property_name)