Casting foreign_keys to a list in order to index into it.

Fixes bug 888839

Change-Id: I66307cb355120b992913c8a1d8d5855b30f70504

glance/registry/db/migrate_repo/versions/012_id_to_uuid.py

@@ -229,8 +229,8 @@ def _get_table(table_name, metadata):
 
 def _get_foreign_keys(t_images, t_image_members, t_image_properties):
     """Retrieve and return foreign keys for members/properties tables."""
-    image_members_fk_name = t_image_members.foreign_keys[0].name
-    image_properties_fk_name = t_image_properties.foreign_keys[0].name
+    image_members_fk_name = list(t_image_members.foreign_keys)[0].name
+    image_properties_fk_name = list(t_image_properties.foreign_keys)[0].name
 
     fk1 = migrate.ForeignKeyConstraint([t_image_members.c.image_id],
                                        [t_images.c.id],