CBL-13:  since child processes might terminate by themselves, protect
         kill statements from returning nonzero, in final

Change-Id: I1415de7246b7bb55a5668b16c70337afaabef820
Reviewed-on: http://review.couchbase.org/37696
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>