retry without same redirection mirror on 404 errors

retry without same redirection mirror on 404 errors

If 9b8034a9fd40b4d05075fda719e61f6eb4c45678 serves the Release files
from a partial mirror we will end up getting 404 for some of the
indexes. Instead of giving up, we will instead ignore our same
redirection mirror constrain and ask the redirection service as a
potential hashsum mismatch is better than keeping the certain 404 error.