RFC 7231 permits HEAD requests to contain a body, although it does
state there are no defined semantics for payloads of HEAD requests
and that some servers may reject HEAD requests with a payload.
Accept HEAD requests with a body.
Fix a bug where a HEAD request with a chunked body would interpret
the body as the headers for the next request on the connection.
For #53960.
Change-Id: I83f7112fdedabd6d6291cd956151d718ee6942cd
Reviewed-on: https://go-review.googlesource.com/c/go/+/418614
Run-TryBot: Damien Neil <dneil@google.com> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>