buildfarm git references pointing at github?

If you go to, say,

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=koreaceratops&dt=2017-03-13%2020%3A49%3A29

and check the git links near the bottom of the page, you'll notice they
all point at github, not at git.postgresql.org. I do not like that,
first because I do not consider github to be an authoritative source
for this purpose, and second because the links are all 404 anyway.

Some other nearby pages have only some of the links pointing at github,
but why are any of them doing that?

regards, tom lane