No longer need subprocess wrapping there :)

plugins/provisioners/chef/provisioner/chef_client.rb

@@ -114,7 +114,6 @@ module VagrantPlugins
           # Knife is not part of the current Vagrant bundle, so it needs to run
           # in the context of the system.
           Vagrant.global_lock do
-            Vagrant::Util::Env.with_clean_env do
             command = ["knife", deletable, "delete", "--yes", node_name]
             r = Vagrant::Util::Subprocess.execute(*command)
             if r.exit_code != 0
@@ -130,4 +129,3 @@ module VagrantPlugins
     end
   end
 end
-end