Pass a proper Pathname for SSHExec to check key perms

lib/vagrant/action/builtin/ssh_exec.rb

@@ -1,3 +1,5 @@
+require "pathname"
+
 require "vagrant/util/ssh"
 
 module Vagrant
@@ -26,8 +28,10 @@ module Vagrant
           # not yet ready for SSH, so we raise this exception.
           raise Errors::SSHNotReady if info.nil?
 
-          # Check the SSH key permissions
-          SSH.check_key_permissions(info[:private_key_path])
+          if info[:private_key_path]
+            # Check the SSH key permissions
+            SSH.check_key_permissions(Pathname.new(info[:private_key_path]))
+          end
 
           # Exec!
           SSH.exec(info, env[:ssh_opts])

test/unit/vagrant/action/builtin/ssh_exec_test.rb

@@ -30,8 +30,10 @@ describe Vagrant::Action::Builtin::SSHExec do
   end
 
   it "should check key permissions then exec" do
+    machine_ssh_info[:private_key_path] = "/foo"
+
     ssh_klass.should_receive(:check_key_permissions).
-      with(machine_ssh_info[:private_key_path]).
+      with(Pathname.new(machine_ssh_info[:private_key_path])).
       once.
       ordered