Fix authenticate_refresh_token

Author: lepture

website/oauth2.py

@@ -49,7 +49,7 @@ def authenticate_user(self, username, password):
 class RefreshTokenGrant(grants.RefreshTokenGrant):
     def authenticate_refresh_token(self, refresh_token):
         token = OAuth2Token.query.filter_by(refresh_token=refresh_token).first()
-        if token and not token.revoked and not item.is_refresh_token_expired():
+        if token and not token.revoked and not token.is_refresh_token_expired():
             return token
 
     def authenticate_user(self, credential):