Set flavor for api pipeline explicitly

Change-Id: I43937f0435a33b74a1b338c4be4707788a3232db
diff --git a/glance/files/queens/glance-api.conf.Debian b/glance/files/queens/glance-api.conf.Debian
index 654f077..ab35de6 100644
--- a/glance/files/queens/glance-api.conf.Debian
+++ b/glance/files/queens/glance-api.conf.Debian
@@ -1787,6 +1787,7 @@
 #
 #  (string value)
 #flavor = keystone
+flavor = keystone
 
 #
 # Name of the paste configuration file.