CBLT-195:  don't break CHOICE params to Jenkins jobs

Change-Id: I2cf8b2b377dd42888b38c40b6e871d1f0c735950
Reviewed-on: http://review.couchbase.org/37973
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>