MB-8886:  roll back libvbucket to last known good

Change-Id: I929e7fbd5642c4cf2e1532a36275a7bd64591a2a
Reviewed-on: http://review.couchbase.org/28381
Tested-by: Philip Labee <philip@couchbase.com>
Reviewed-by: Chiyoung Seo <chiyoung.seo@gmail.com>
Reviewed-by: Philip Labee <philip@couchbase.com>