net/url: scheme gets lost for opaque paths

[dvyukov]

The following program fails with the panic:

package main

import (
    "bufio"
    "bytes"
    "net/http"
)

func main() {
    data := []byte("GET http:@ HTTP/1.1\n\n")
    r, err := http.ReadRequest(bufio.NewReader(bytes.NewReader(data)))
    if err != nil {
        return
    }
    buf := new(bytes.Buffer)
    if err := r.Write(buf); err != nil {
        return
    }
    _, err = http.ReadRequest(bufio.NewReader(buf))
    if err != nil {
        panic(err)
    }
}

panic: parse @: invalid URI for request

Scheme gets parsed into URL.Scheme, but then it is not written during serialization of URL with opaque path.
The same happens in the net/url Opaque Example: https scheme gets lost.

go version devel +a1fe3b5 Sat Jun 13 04:33:26 2015 +0000 linux/amd64

[dvyukov]

This is probably WAI because scheme is not including unless we send request to proxy. Is it correct?

[rsc]

This is working as intended.
The scheme is discarded and the host is moved to the Host: header.