Don't use Try/Catch for admin methmap

This behaves strangely on py3 when trying to capture memory leaks.

Change-Id: Iea3de67fa8d97201355b55b6b4e03507ff535d77
Reviewed-on: http://review.couchbase.org/26658
Reviewed-by: Mordechai Nunberg <mnunberg@haskalah.org>
Tested-by: Mordechai Nunberg <mnunberg@haskalah.org>