Without this patch, we encountered the following problem while starting horizon:
Jul 06 15:32:22 host-172-16-1-76 python[4047]: CommandError: An error occurred during rendering /usr/share/openstack-dashboard/openstack_dashboard/templates/_stylesheets.html: Don't know how to merge conflicting combinators: <SimpleSelector: u'+ .btn:not(:first-child)'> and <SimpleSelector: u'> .btn'>
Change-Id: Ie558f0c00a1f915b49180f6ef090b8ba97c9b30a
Signed-off-by: luyao <lu.yao135@zte.com.cn>