MB-11828 upr client: Fix badmatch due to use of bound variable

Change-Id: I4433732fc812d9a94658d463581bb4f668e6ebbd
Reviewed-on: http://review.couchbase.org/39988
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Reviewed-by: Nimish Gupta <nimish@couchbase.com>
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Volker Mische <volker.mische@gmail.com>