Fixed #20819 -- Return 404 instead of 500 error when `staticfiles` view is used in production.

django/contrib/staticfiles/views.py

@@ -11,7 +11,6 @@ except ImportError:     # Python 2
     from urllib import unquote
 
 from django.conf import settings
-from django.core.exceptions import ImproperlyConfigured
 from django.http import Http404
 from django.views import static
 
@@ -31,9 +30,7 @@ def serve(request, path, insecure=False, **kwargs):
     It uses the django.views.static view to serve the found files.
     """
     if not settings.DEBUG and not insecure:
-        raise ImproperlyConfigured("The staticfiles view can only be used in "
-                                   "debug mode or if the --insecure "
-                                   "option of 'runserver' is used")
+        raise Http404
     normalized_path = posixpath.normpath(unquote(path)).lstrip('/')
     absolute_path = finders.find(normalized_path)
     if not absolute_path: