debian: don't set syslog handlers for django_select2 if undefined (#36787)

debian/multitenant/debian_config.py

@@ -28,11 +28,13 @@ LOGGING['filters'].update({
 })
 for handler in LOGGING['handlers'].values():
     handler.setdefault('filters', []).append('cleaning')
-# django_select2 outputs debug message at level INFO
-LOGGING['loggers']['django_select2'] = {
-    'handlers': ['syslog'],
-    'level': 'WARNING',
-}
+
+if 'syslog' in LOGGING['handlers']:
+    # django_select2 outputs debug message at level INFO
+    LOGGING['loggers']['django_select2'] = {
+        'handlers': ['syslog'],
+        'level': 'WARNING',
+    }
 
 # Default login's form username label
 A2_USERNAME_LABEL = _('Email')