Fix race creating EvalFuture
Fix race creating EvalFuture

This PR fixes https://github.com/hashicorp/nomad/issues/3044

burdandrei/nomad,hashicorp/nomad,nak3/nomad,hashicorp/nomad,frundh/nomad,dvusboy/nomad,burdandrei/nomad,Ashald/nomad,frundh/nomad,burdandrei/nomad,Ashald/nomad,Ashald/nomad,dvusboy/nomad,dvusboy/nomad,frundh/nomad,dvusboy/nomad,hashicorp/nomad,Ashald/nomad,nak3/nomad,nak3/nomad,frundh/nomad,frundh/nomad,dvusboy/nomad,hashicorp/nomad,nak3/nomad,Ashald/nomad,dvusboy/nomad,burdandrei/nomad,hashicorp/nomad,burdandrei/nomad,nak3/nomad,Ashald/nomad,burdandrei/nomad,nak3/nomad,frundh/nomad,hashicorp/nomad,burdandrei/nomad,nak3/nomad,Ashald/nomad,dvusboy/nomad,frundh/nomad