Force at least one retry in vm_exists? for provider VirtualBox 4.3
 * Due to VirtualBox 13190, on Windows, `VBoxManager showvminfo` crashes
   if the VM is suspended (and maybe in other occasions). This leads Vagrant
   to think the VM does not exist. This has bad consequences for lot of
   commands since machine uuid is cleared which leads to a new VM being
   started. Since there is already a retry mechanism in place, simply force
   at least one retry of the command. The second invocation should work
   correctly if the machine is present.