CA-185733: RPU XenCenter stuck on upgrade screen if connected as XS Pool Admin
CA-185733: RPU XenCenter stuck on upgrade screen if connected as XS Pool Admin

Before xapi_session.do_external_auth, we should check the external
auth service status at first.

Signed-off-by: Phus Lu <029e184aefbd8f8732df805042602d8618004d6a@citrix.com>

thomassa/xen-api,jjd27/xen-api,euanh/xen-api,Frezzle/xen-api,srowe/xen-api,euanh/xen-api,thomassa/xen-api,jjd27/xen-api,Frezzle/xen-api,jjd27/xen-api,rafalmiel/xen-api,Frezzle/xen-api,thomassa/xen-api,Frezzle/xen-api,rafalmiel/xen-api,euanh/xen-api,srowe/xen-api,simonjbeaumont/xen-api,rafalmiel/xen-api,rafalmiel/xen-api,thomassa/xen-api,jjd27/xen-api,euanh/xen-api,simonjbeaumont/xen-api,srowe/xen-api,euanh/xen-api,simonjbeaumont/xen-api,rafalmiel/xen-api,jjd27/xen-api,thomassa/xen-api,Frezzle/xen-api,euanh/xen-api,simonjbeaumont/xen-api,thomassa/xen-api,srowe/xen-api,jjd27/xen-api,srowe/xen-api,rafalmiel/xen-api,simonjbeaumont/xen-api,simonjbeaumont/xen-api