Revert "avoid mutating datum in idempontent"
Revert "avoid mutating datum in idempontent"

This reverts commit dc635a574ab70385e2fecc05d41a67e4b2636214.

excon/excon,mahemoff/excon,TheNeatCompany/excon,hammerdr/excon,liftforward/excon,wadetandy/excon,ilackarms/excon,cloudfoundry-incubator/excon