name := headerValue(req.Header, a.nameHeaders.Value())
	if len(name) == 0 {
		return nil, false, nil
	}
	groups := allHeaderValues(req.Header, a.groupHeaders.Value())
	extra := newExtra(req.Header, a.extraHeaderPrefixes.Value())

	// clear headers used for authentication
	ClearAuthenticationHeaders(req.Header, a.nameHeaders, a.groupHeaders, a.extraHeaderPrefixes)

	return &authenticator.Response{

  _cgoexp_[0-9a-z]+_goCallback\(\)
      .*_cgo_gotypes\.go:[0-9]+ \+0x[0-9,a-f]+
  _cgoexp_[0-9a-z]+_goCallback\(\)
      <autogenerated>:1 \+0x[0-9,a-f]+

Goroutine [0-9] \(running\) created at:
  runtime\.newextram\(\)
      .*/runtime/proc.go:[0-9]+ \+0x[0-9,a-f]+
==================`,
		`==================
WARNING: DATA RACE
Read at 0x[0-9,a-f]+ by .*:
  main\..*
      .*/main\.go:[0-9]+ \+0x[0-9,a-f]+(?s).*

			ncopy, err = t.doBodyCopy(dst, body)
		} else {
			ncopy, err = t.doBodyCopy(w, io.LimitReader(body, t.ContentLength))
			if err != nil {
				return err
			}
			var nextra int64
			nextra, err = t.doBodyCopy(io.Discard, body)
			ncopy += nextra
		}
		if err != nil {
			return err
		}
	}
	if t.BodyCloser != nil {
		closed = true
		if err := t.BodyCloser.Close(); err != nil {
			return err
		}

	gp.m.winsyscall = winsyscall
}

func cgocallbackg1(fn, frame unsafe.Pointer, ctxt uintptr) {
	gp := getg()

	if gp.m.needextram || extraMWaiters.Load() > 0 {
		gp.m.needextram = false
		systemstack(newextram)
	}

	if ctxt != 0 {
		s := append(gp.cgoCtxt, ctxt)

		// Now we need to set gp.cgoCtxt = s, but we could get
		// a SIGPROF signal while manipulating the slice, and

	if _cgo_pthread_key_created != nil && *(*uintptr)(_cgo_pthread_key_created) != 0 {
		cgoBindM()
	}
}

// newextram allocates m's and puts them on the extra list.
// It is called with a working local m, so that it can do things
// like call schedlock and allocate.
func newextram() {
	c := extraMWaiters.Swap(0)
	if c > 0 {
		for i := uint32(0); i < c; i++ {
			oneNewExtraM()
		}