not ssh:. I'm not sure that ssh: has ever worked --- wouldn't it require an account on the target machine?
That's correct.
ssh works if you have committer access on the repo at git.postgresql.org. Since the main postgresql.git repo there is a mirror only, nobody has commit access there, so it doesn't work (but there are other repos hosted on the same server that does have committers). But for the postgresql.git repo, it has never worked on that server.