RFA: fix PR bootstrap/58572

[Tom Tromey]

>>>>> "Jeff" == Jeff Law <law@redhat.com> writes:

Jeff> But isn't the whole point of bootstrap-lean to remove those
Jeff> directories during the build?

Yeah, but I think they are still mostly removed.
We just keep the "last previous" stage around for the benefit of
"install".

It's possible I'm missing something, though, since I haven't ever even
tried bootstrap-lean before.

Tom