I hit an error here where the arguments weren't strings. Maybe I'm not calling this the way you expected.
```
 INFO subprocess: Starting process: ["/usr/bin/sudo", "/usr/bin/lxc-vagrant-wrapper", "lxc-clone", "-o", #<Vagrant::Config::V2::DummyConfig:0x007f5c59b5e9d0>, "-n", #<Vagrant::Config::V2::DummyConfig:0x007f5c59b5e8b8>]
ERROR warden: Error occurred: all arguments must be String: ["/usr/bin/sudo", "/usr/bin/lxc-vagrant-wrapper", "lxc-clone", "-o", #<Vagrant::Config::V2::DummyConfig:0x007f5c59b5e9d0>, "-n", #<Vagrant::Config::V2::DummyConfig:0x007f5c59b5e8b8>]
```