Short circuit the deploy command if the Heat stack is in progress (create/update/delete)

[Dougal Matthews]

At the moment, python-tripleoclient will take a number of steps before it hits an error and determines that it can't deploy. It will remove files from the current plan, update the plan with the new files and attempt to deploy (which is when it will error).

At the very start, it should check to see if the Heat stack exists. If it is in progress, it can just stop at that point.

[Emilien Macchi (emilienm)]

This is an automated cleanup. This bug report has been closed because it
is older than 18 months and there is no open code change to fix this.
After this time it is unlikely that the circumstances which lead to
the observed issue can be reproduced.

If you can reproduce the bug, please:
* reopen the bug report (set to status "New")
* AND add the detailed steps to reproduce the issue (if applicable)
* AND leave a comment "CONFIRMED FOR: <RELEASE_NAME>"
  Only still supported release names are valid (FUTURE, PIKE, QUEENS, ROCKY, STEIN).
  Valid example: CONFIRMED FOR: FUTURE