PREVIEW_LMS_BASE must now be set (default value does not work for both edge and edx).

https://edx.lighthouseapp.com/projects/102637/tickets/331

cms/djangoapps/contentstore/utils.py

@@ -88,7 +88,7 @@ def get_lms_link_for_item(location, preview=False, course_id=None):
 
     if settings.LMS_BASE is not None:
         if preview:
-            lms_base = settings.MITX_FEATURES.get('PREVIEW_LMS_BASE', 'preview.' + settings.LMS_BASE)
+            lms_base = settings.MITX_FEATURES.get('PREVIEW_LMS_BASE')
         else:
             lms_base = settings.LMS_BASE
 

cms/djangoapps/contentstore/views/component.py

@@ -179,8 +179,7 @@ def edit_unit(request, location):
             break
         index = index + 1
 
-    preview_lms_base = settings.MITX_FEATURES.get('PREVIEW_LMS_BASE',
-                                                  'preview.' + settings.LMS_BASE)
+    preview_lms_base = settings.MITX_FEATURES.get('PREVIEW_LMS_BASE')
 
     preview_lms_link = '//{preview_lms_base}/courses/{org}/{course}/{course_name}/courseware/{section}/{subsection}/{index}'.format(
         preview_lms_base=preview_lms_base,