Merge pull request #16840 from edx/bmedx/django111_conditional_birdcage

Make all uses of birdcage conditional, should fix 1.11 errors

cms/envs/common.py

@@ -45,6 +45,9 @@ import imp
 import os
 import sys
 from datetime import timedelta
+
+import django
+
 import lms.envs.common
 # Although this module itself may not use these imported variables, other dependent modules may.
 from lms.envs.common import (
@@ -433,6 +436,13 @@ simplefilter('ignore')
 
 ################################# Middleware ###################################
 
+# TODO: Remove Django 1.11 upgrade shim
+# SHIM: Remove birdcage references post-1.11 upgrade as it is only in place to help during that deployment
+if django.VERSION < (1, 9):
+    _csrf_middleware = 'birdcage.v1_11.csrf.CsrfViewMiddleware'
+else:
+    _csrf_middleware = 'django.middleware.csrf.CsrfViewMiddleware'
+
 MIDDLEWARE_CLASSES = [
     'crum.CurrentRequestUserMiddleware',
     'request_cache.middleware.RequestCache',
@@ -442,7 +452,7 @@ MIDDLEWARE_CLASSES = [
     'openedx.core.djangoapps.header_control.middleware.HeaderControlMiddleware',
     'django.middleware.cache.UpdateCacheMiddleware',
     'django.middleware.common.CommonMiddleware',
-    'birdcage.v1_11.csrf.CsrfViewMiddleware',
+    _csrf_middleware,
     'django.contrib.sites.middleware.CurrentSiteMiddleware',
 
     # Instead of SessionMiddleware, we use a more secure version