CBQE-0: added logs if get_all_builds raise Exception

Change-Id: I5cc494f726d7889a6f106ae625d7120c8f333973
Reviewed-on: http://review.couchbase.org/30313
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>