MB-100: Remove unused variables and redundent assignments

Change-Id: Ic31c276a06c09f91e6cbf5ddaf9accb7184761df
Reviewed-on: http://review.couchbase.org/24335
Reviewed-by: Chiyoung Seo <chiyoung.seo@gmail.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>