general: always declare django-mellon if it's available (#23362)

chrono/settings.py

@@ -136,6 +136,7 @@ except ImportError:
     mellon = None
 
 if mellon is not None:
+    INSTALLED_APPS += ('mellon',)
     AUTHENTICATION_BACKENDS = (
         'mellon.backends.SAMLBackend',
         'django.contrib.auth.backends.ModelBackend',

debian/debian_config.py

@@ -4,9 +4,6 @@ import os
 
 PROJECT_NAME = 'chrono'
 
-# SAML2 authentication
-INSTALLED_APPS += ('mellon',)
-
 #
 # hobotization (multitenant)
 #

tests/settings.py

@@ -1,3 +1,2 @@
 TIME_ZONE = 'Europe/Paris'
 LANGUAGE_CODE = 'en-us'
-INSTALLED_APPS = INSTALLED_APPS + ('mellon',)