CBQE-928: fix upgrade test with ports

Change-Id: Ie42f93819d554744f0d6ff2818ad018f02d72b7c
Reviewed-on: http://review.couchbase.org/26197
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>