Actually, always rollback the datanommer session

Signed-off-by: Aurélien Bompard <aurelien@bompard.org>

fedbadges/consumer.py

@@ -120,12 +120,11 @@ def __call__(self, message: Message):
             self._process_message(message)
         except SQLAlchemyError:
             log.exception("Could not process message %s on %s", message.id, message.topic)
-            # If we don't rollback, following queryies will fail.
+            # If we don't rollback, following queryies will fail: https://sqlalche.me/e/20/8s2b
             self.tahrir.session.rollback()
+        finally:
+            # Always finish the datanommer transaction with a rollback, it's read-only.
             datanommer.models.session.rollback()
-            # Also rollback the connection to avoid https://sqlalche.me/e/20/8s2b
-            self.tahrir.session.connection().rollback()
-            datanommer.models.session.connection().rollback()
 
     def _process_message(self, message: Message):
         # First thing, we receive the message, but we put ourselves to sleep to