Merge pull request #696 from wallyworld/keep-broken-part-2

Port from 1.20

Do not stop bootstrap instance on error if keep-broken flag is true

Fixes: https://bugs.launchpad.net/bugs/1365772

The --keep-broken flag was added for 1.20.7 and it did stop the environment from being destroyed on a failed bootstrap, but did not stop the bootstrap instance from being stopped. This PR adds in the extra logic to do that.