This was unrelated to yesterday's problem.
It seems that Rackspace deaggregated their /19 into thirty one /24s:
http://www.ris.ripe.net/dashboard/209.20.64.0/19
and Jump does not accept /24 announcements. I've got them to put an
exception in and have asked Rackspace to put a covering route, so it
works now.
They do if that was the size of the allocation, the problem is with
deaggregation, not the size of the announcement, iirc