caches: call 'repo.updatecache()' in 'repo.destroyed()'
Regenerating the cache after a 'strip' or a 'rollback' is useful. So we call the
generic cache warming function as other caches than just branchmap will be
updated there in the future.
To do so, we have to make 'repo.updatecache()' able to take no arguments. In
such cases, we reload all caches.