automatic key insertion is stuck

[msimonin]

When vagrant detects an insecure key it tries to automatically inject a new one.
This works fine until vagrant tries to close the connection (made with the original one) before reconnecting with the new key. Vagrant stucks on closing the connection.
Killing the corresponding ssh process makes vagrant to progress but isn't a right workaround.

As a workaround one may use config.ssh.insert_key=false in the Vagrantfile.
It will prevent Vagrant to inject the new key in the vm.