Updated openstack/openstack
Project: openstack/horizon  6539deb4241abbcc48fe80cfa78d561981066046

Fix hide drop_arrow.png if only one tenant

when user only in one tenant, the tenant region show drop_arrow.png,
this will confuse user. It needs to hide.

Closes-bug:#1316471

Change-Id: I9f1fefcc6a23e6e6a555a59df6ae7f50d65edbe2