fix 404s for Github Enterprise repos
fix 404s for Github Enterprise repos

This is a slightly more flexible solution for #19 than
d2c1d98deb169f2539668d6992207a9e9d83b8dd, which worked for private
github.com repos but not for repos on a different domain.

etsy/Hound,matthewdoerksen-porch/Hound,flowbywind/hound,gwindes/Hound,miketheman/hound,etsy/Hound,miketheman/hound,rberrelleza/hound,snowsnail/hound,snowsnail/hound,flowbywind/hound,morria/hound,mrKrizz/hound,colbyr/hound,etsy/Hound,matthewdoerksen-porch/Hound,rberrelleza/hound,sstarcher/Hound,mrKrizz/hound,gwindes/Hound,sstarcher/Hound,Kareo/Hound,dnephin/hound,0xmohit/hound,mrKrizz/hound,sstarcher/Hound,rberrelleza/hound,flowbywind/hound,0xmohit/hound,dnephin/hound,mrKrizz/hound,Kareo/Hound,colbyr/hound,matthewdoerksen-porch/Hound,snowsnail/hound,morria/hound,Kareo/Hound,miketheman/hound,gwindes/Hound,dnephin/hound,snowsnail/hound,sstarcher/Hound,Kareo/Hound,morria/hound,dnephin/hound,0xmohit/hound,morria/hound,flowbywind/hound,colbyr/hound,etsy/Hound,miketheman/hound,colbyr/hound,matthewdoerksen-porch/Hound,gwindes/Hound,rberrelleza/hound,0xmohit/hound,Kareo/Hound