Permit DMI change when host is in build mode
This is a bit of a corollary to the existing `host_profile_assume` setting.
I'd like to prevent a host from registering with a different DMI than is on record, unless the host is in "build" mode.
If I'm rebuilding a host in my Cloud Infra, the DMI might change. When the host is not being rebuilt, I'd like to prevent a different host from snagging the subscription information (by setting host_profile_assume == false). But if I've set the host to be rebuilt, I'm expecting a new subscription for the host.