Comment 2 for bug 1853575

some notes:
there is also several bugs in rebuilding pinned instances:
https://bugs.launchpad.net/nova/+bug/1763766
https://bugs.launchpad.net/nova/+bug/1750623
https://bugs.launchpad.net/nova/+bug/1750618
https://bugs.launchpad.net/nova/+bug/1772523

Proper fix will require time because upstream developers currently in "discussion" stage of the fix. We will provide dangerous workaround (it will be part of the whole fix): without additional "image validation" it is dangerous if rebuild is using new image with different cpu requirements; customer should handle it). Also I'm identifying required fixes from the bugs above and backporting needed.