Go HTTP implements the 418 I'm a Teapot status code in go/src/net/http/status.go.

Its reference is RFC7168, but really came from RFC2324, Hyper Text Coffee Pot Control Protocol (HTCPCP/1.0). Note the title - HTCPCP/1.0 is not HTTP/1.x.

HTCPCP was an April 1 joke by Larry to illustrate how people were abusing HTTP in various ways. Ironically, it's not being used to abuse HTTP itself -- people are implementing parts of HTCPCP in their HTTP stacks.

Node's support for the HTCPCP 418 I'm a Teapot status code (seenodejs/node#14644) has been used as an argument in the HTTP Working Group to preclude use of 418 in HTTP for real-world purposes.

While we have a number of spare 4xx HTTP status codes that are unregistered now, the semantics of HTTP are something that (hopefully) are going to last for a long time, so one day we may need this code point.

Please consider removing support for 418 from Go HTTP, since it's not a HTTP status code (even by its own definition). I know it's amusing, I know that a few people have knocked up implementations for fun, but it shouldn't pollute the core protocol; folks can extend Go easily enough if they want to play with non-standard semantics.

Thanks,

/cc@bradfitz