CBQE-1119: minor fix in couchbase-cli tests

Change-Id: I325086380d510cc7c81a00904b31d812e867166e
Reviewed-on: http://review.couchbase.org/26119
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>