When trying to use Alberta or Bishop mirrors in HTTP, they don't work. Both don't work using HTTP. Both seem to work using FTP (only tested with a manual FTP). As far as I can see on the Alberta site, they don't even have a GENTOO section in the directory hierarchy. I can't tell what's happening with the Bishop site but it looks like they don't offer HTTP download at all. Reproducible: Always Steps to Reproduce: 1. 2. 3.
Those mirrors do not offer HTTP interfaces for their mirrors.