Merge pull request #1468 from MITx/feature/ichuang/fix-module-staff-access-v2

fix module staff accesss - by has_access, not by user.is_staff

lms/djangoapps/courseware/module_render.py

@@ -280,6 +280,7 @@ def _get_module(user, request, descriptor, student_module_cache, course_id,
         # Make an error module
         return err_descriptor.xmodule_constructor(system)(None, None)
 
+    system.set('user_is_staff', has_access(user, descriptor.location, 'staff', course_id))
     _get_html = module.get_html
 
     if wrap_xmodule_display == True: