Fix user details update

social_auth/backends/__init__.py

@@ -214,7 +214,7 @@ def update_user_details(self, user, response, details, is_new=False):
                 # do not update username, it was already generated by
                 # self.username(...) and loaded in given instance
                 if name != USERNAME and value and value != getattr(user, name,
-                                                                   value):
+                                                                   None):
                     setattr(user, name, value)
                     changed = True