Fix sqlalchemy grouping on v1 storage

This fixes "CompileError: Can't resolve label reference for
ORDER BY / GROUP BY." error messages raised by sqlalchemy when the groupby
expression includes a comma.

Change-Id: Ia253175b45b8222aaee415ea535fa4102312be5a

cloudkitty/storage/v1/sqlalchemy/__init__.py

@@ -119,7 +119,7 @@ class SQLAlchemyStorage(storage.BaseStorage):
             self.frame_model.end <= end,
             self.frame_model.res_type != '_NO_DATA_')
         if groupby:
-            q = q.group_by(groupby)
+            q = q.group_by(sqlalchemy.sql.text(groupby))
 
         # Order by sum(rate)
         q = q.order_by(sqlalchemy.func.sum(self.frame_model.rate))

releasenotes/notes/fix-v1-storage-groupby-e865d1315bd390cb.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    ``CompileError: Can't resolve label reference for ORDER BY / GROUP BY.``
+    errors that were sometimes raised by SQLAlchemy when using the v1 storage
+    backend and grouping on ``tenant_id`` and ``res_type`` have been fixed.