Code review comment for lp:~axwalk/juju-core/juju-failed-bootstrap-destroy-jenv

I'm not sure about this. I think we're getting to the point where the
mental model is getting too complicated and exposes too much of Juju's
internals. Why not just go ahead and remove the jenv file automatically
under the circumstances described ie no previous jenv file, bootstrap
fails, destroy files, so remove jenv.
What's the use case for stand alone use of the --config-only option? If
the cloud artefacts are already gone, we could just inform the user that
their cloud env has disappeared and did they want to clean up the
remaining local config, and if they say yes, just do it.

https://codereview.appspot.com/59560043/