Fixed a Dokku App that is "Locked" due to a Previously Interrupted Build or Deploy

Just got this new error when trying to deploy to a Dokku box:

remote: app is currently being deployed or locked. Waiting...

This can happen if a previous build and deploy was interrupted by you or the origin server or if the app crashes in a live box and Dokku is unaware for some reason.

With a little investigating and it appears Dokku locks by creating an empty hidden file:

/home/dokku/your-app/.build.lock

// or it may be called
/home/dokku/your-app/.deploy.lock

Deleting these files will fix your problem.