Merge pull request #1647 from levimalott/fix/recover-from-failed-clea…

…nup-rollbacks

Log, but allow, failures during cleanup rollbacks.

core/dbt/adapters/base/connections.py

@@ -248,7 +248,13 @@ def commit(self):
     @classmethod
     def _rollback_handle(cls, connection):
         """Perform the actual rollback operation."""
-        connection.handle.rollback()
+        try:
+            connection.handle.rollback()
+        except Exception:
+            logger.debug(
+                'Failed to rollback {}'.format(connection.name),
+                exc_info=True
+            )
 
     @classmethod
     def _close_handle(cls, connection):