Don't error check the "exit" call to SSH

lib/vagrant/ssh/session.rb

@@ -20,17 +20,20 @@ module Vagrant
       def shell
         session.shell do |sh|
           sh.on_process_run do |sh, process|
+            # Enable error checking by default
+            process.properties[:error_check] = true if !process.properties.has_key?(:error_check)
+
             process.on_finish do |p|
               # By default when a process finishes we want to check the exit
               # status so we can properly raise an exception
-              self.check_exit_status(p.exit_status, p.command, p.properties)
+              self.check_exit_status(p.exit_status, p.command, p.properties) if p.properties[:error_check]
             end
           end
 
           yield sh
 
           # Exit and wait. We don't run shell commands in the background.
-          sh.execute "exit"
+          sh.execute "exit", :error_check => false
           sh.wait!
         end
       end