run-tests.py: allow returncodes to be one of a list of items

wget on RHEL5 (wget 1.11.4, python 2.4) returns 1 when hitting a HTTP 403 Forbidden
error, but returns an 8 on newer versions of wget (wget 1.14).
Therefore, we have to be able to accept either, while still checking
we got a 403 error.