title: vagrant up hangs on ssh
body: <p>I did <code>vagrant up --provision libvirt</code> and it hangs on:</p>
  
  <pre><code>default: Waiting for SSH to become available...
  </code></pre>
  
  <p>I can do <code>vagrant ssh</code>. it works! but I can't understand why vagrant up hangs on ssh mode.
  I delete all the machine from my local. build again. doesnt solve an issue.
  Also, reinstall plugins doesn't help.
  Also, delete the .vagrant file from my repo!
  I remove inscure-keypair from .vagrant.d
  I did <code>vagrant reload</code></p>
  
  <p>The issue is this error actually:</p>
  
  <pre><code>An action 'up' was attempted on the machine 'default',
  but another process is already executing an action on the machine.
  Vagrant locks each machine for access by only one process at a time.
  Please wait until the other Vagrant process finishes modifying this
  machine, then try again.
  
  If you believe this message is in error, please check the process
  listing for any "ruby" or "vagrant" processes and kill them. Then
  try again.
  </code></pre>
  
  <p>I killed all ruby and vagrant process but doesn't help
  Vagrant version: 1.9.4
  vagrant-libvirt version: 0.0.37
  ubuntu 16.04</p>