Comment 2 for bug 1815697

I was hoping that maybe Dan's change here would help with the API startup issue:

https://review.openstack.org/#/c/623283/

but that won't cache the minimum compute version until it gets a non-0 minimum which I don't think will happen while there is a down cell.

I wonder if we could enhance that code to filter out disabled cells? So if you have a down cell, you disable it and then we exclude it from the cache results because the scheduler shouldn't pick it for anything (new server creates or move operations).

Other things I was thinking about are if we can make the _determine_version_cap result a global or singleton or something so that each of the 31 nova.compute.api.API initializations don't go through the same cell timeout loop to find out there is a down cell and hang the API.