CBQE-0: handle RuntimeError: maximum recursion depth exceeded

test hangs when we can't setMulti (_setMulti_seq) -> recursion many times and python throws RuntimeError: maximum recursion depth exceeded
http://qa.hq.northscale.net/job/centos_x64--02_01--basic_rebalance_tests-P0/8/consoleFull

Change-Id: I899e6e4a9d62d2b3c027a4fd997c787d4b801346
Reviewed-on: http://review.couchbase.org/34383
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>