fun Directory.parentOrRoot(): Directory = if (this.file("version.txt").asFile.exists()) {
    this
} else {
    val parent = dir("..")
    when {
        parent.file("version.txt").asFile.exists() -> parent
        this == parent -> throw IllegalStateException("Cannot find 'version.txt' file in root of repository")
        else -> parent.parentOrRoot()
    }