CBQE-2011 fixed hang windows backup and
restore jobs

Change-Id: Idf250a1839d38a53016a72f936aa7e84651543fc
Reviewed-on: http://review.couchbase.org/33715
Reviewed-by: Aruna Piravi <aruna@couchbase.com>
Tested-by: Thuan Nguyen <soccon@gmail.com>
Tested-by: buildbot <build@couchbase.com>