CBQE-0: fix in upgradeXDCR.py

Change-Id: I94d9c02a3b1fb2a2551ee51bcb03bf83f1b167b4
Reviewed-on: http://review.couchbase.org/30306
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>