Greetings,
The current docs say that if a client asks for a protocol that the backend
doesn't support, it will return the newest minor version.
https://www.postgresql.org/docs/current/protocol-message-formats.html#PROTOCOL-MESSAGE-FORMATS-NEGOTIATEPROTOCOLVERSION
However that isn't what it returns. It actually returns the entire newest
protocol that it supports. Attached is a patch to fix the docs.
Dave Cramer