Switch from exception logging middleware to a django signal handler, so that...

Switch from exception logging middleware to a django signal handler, so that we no longer swallow Http404 exceptions and turn them into 500 errors

cms/envs/common.py

@@ -116,6 +116,7 @@ MIDDLEWARE_CLASSES = (
 )
 
 ############################ SIGNAL HANDLERS ################################
+# This is imported to register the exception signal handling that logs exceptions
 import monitoring.exceptions  # noqa
 
 ############################ DJANGO_BUILTINS ################################

common/djangoapps/util/middleware.py

-import logging
-
-from django.conf import settings
-from django.http import HttpResponseServerError
-
-log = logging.getLogger("mitx")
-
-class ExceptionLoggingMiddleware(object):
-    """Just here to log unchecked exceptions that go all the way up the Django 
-    stack"""
-
-    if not settings.TEMPLATE_DEBUG:
-        def process_exception(self, request, exception):
-            log.exception(exception)
-            return HttpResponseServerError("Server Error - Please try again later.")
-

lms/envs/common.py

@@ -151,6 +151,9 @@ MODULESTORE = {
     }
 }
 
+############################ SIGNAL HANDLERS ################################
+# This is imported to register the exception signal handling that logs exceptions
+import monitoring.exceptions  # noqa
 
 ############################### DJANGO BUILT-INS ###############################
 # Change DEBUG/TEMPLATE_DEBUG in your environment settings files, not here
@@ -262,7 +265,6 @@ TEMPLATE_LOADERS = (
 )
 
 MIDDLEWARE_CLASSES = (
-    'util.middleware.ExceptionLoggingMiddleware',
     'django.middleware.common.CommonMiddleware',
     'django.contrib.sessions.middleware.SessionMiddleware',
     'django.middleware.csrf.CsrfViewMiddleware',