atomic user creation/notification

ttadmin/users/models.py

@@ -246,9 +246,13 @@ def on_townie_pre_save(sender, instance, **kwargs):
     # See if we need to create the user on disk.
     if existing.unreviewed and instance.accepted:
         logger.info('Creating user {} on disk.'.format(instance.username))
+        try:
             instance.create_on_disk()
-        instance.send_welcome_email()
             instance.write_authorized_keys()
+        except Exception as e:
+            logger.error('Failed syncing user {} to disk: {}'.format(instance.username, e)
+        else:
+            instance.send_welcome_email()
         return
     else:
         # This user state transition is currently undefined. In the future, we can check for things