Fixed deleting a cluster while restoring/cloning

[juanpardo]

Summary of changes

Checklist

• Relevant changes are reflected in CHANGES.rst
• Added or changed code is covered by tests
• Documentation has been updated if necessary
• Changed code does not contain any breaking changes (or this is a major version change)

[SStorm]

Very nice solution! Should we make this generic and perhaps move this check into each of the top level handlers in main.py? Even though we've only seen this happen for restore operations, I suspect it can theoretically happen for any?

[juanpardo]

Very nice solution! Should we make this generic and perhaps move this check into each of the top level handlers in main.py? Even though we've only seen this happen for restore operations, I suspect it can theoretically happen for any?

I was expecting you to say that :)
Will add it to this PR