package_ensure_apt not idempotent

[teeler]

The underlying program being executed, add-apt-repository is not idempotent and also, is not available by default, so it should be checked for as well before being executed.

[Lendar]

I think, this is issue is related to repository_ensure_apt, not package_ensure_apt. See:

def repository_ensure_apt(repository):
    sudo("add-apt-repository " + repository)

[teeler]

@Lendar That was in my original comment, the underlying binary add-apt-repository is not idempotent, so calling it directly is not sufficient.