Removed unneccessary creation of new context.

A new context is allocated for callback dispatching,
however it is never actually used.

Change-Id: Ie1ad4308150acf315edcefcb9b1f9ab105e9d166
Reviewed-on: http://review.couchbase.org/26497
Tested-by: Brett Lawson <brett19@gmail.com>
Tested-by: Mordechai Nunberg <mnunberg@haskalah.org>
Reviewed-by: Mordechai Nunberg <mnunberg@haskalah.org>