They 401 when attempting to fetch them from swift:
Sep 15 11:45:13 thumbor1001 thumbor@8813[73737]: thumbor:WARNING ERROR retrieving image http://ms-fe.svc.eqiad.wmnet/v1/AUTH_mw/wikipedia-commons-local-public.f/archive/f/fc/20060131163011!Flag_of_Mexico.svg: HTTP 401: Unauthorized
gilles@thumbor1001:~$ wget http://ms-fe.svc.eqiad.wmnet/v1/AUTH_mw/wikipedia-commons-local-public.f/archive/f/fc/20060131163011\!Flag_of_Mexico.svg --2016-09-15 11:48:23-- http://ms-fe.svc.eqiad.wmnet/v1/AUTH_mw/wikipedia-commons-local-public.f/archive/f/fc/20060131163011!Flag_of_Mexico.svg Resolving ms-fe.svc.eqiad.wmnet (ms-fe.svc.eqiad.wmnet)... 10.2.2.27 Connecting to ms-fe.svc.eqiad.wmnet (ms-fe.svc.eqiad.wmnet)|10.2.2.27|:80... connected. HTTP request sent, awaiting response... 401 Unauthorized Username/Password Authentication Failed.
It's pointing to the wrong shard because the archive/ prefix throws the handler's regexp off.
And I need to double check whether they are saved in the right swift location once generated.