F-10 mock can't build rawhide packages

[Roland McGrath]

> I'm having the same problem:
> 
> rpmdb: Program version 4.5 doesn't match environment version 4.7
> error: db4 error(-30972) from dbenv->open: DB_VERSION_MISMATCH: Database environment version mismatch
> error: cannot open Packages index using db3 -  (-30972)
> error: cannot open Packages database in /var/lib/mock/fedora-11-x86_64/root/var/lib/rpm

When I had those errors on rawhide itself, what was necessary was:
	rm -f /var/lib/rpm/__db.*
Perhaps:
	rm -f /var/lib/mock/fedora-11-x86_64/root/var/lib/rpm/__db.*
would do it?