Fix rpc go routine leak

transport/http_transport.go

@@ -285,8 +285,14 @@ func (h *httpTransportSocket) Recv(m *Message) error {
 
 func (h *httpTransportSocket) Send(m *Message) error {
 	if h.r.ProtoMajor == 1 {
+		// make copy of header
+		hdr := make(http.Header)
+		for k, v := range h.r.Header {
+			hdr[k] = v
+		}
+
 		rsp := &http.Response{
-			Header:        h.r.Header,
+			Header:        hdr,
 			Body:          ioutil.NopCloser(bytes.NewReader(m.Body)),
 			Status:        "200 OK",
 			StatusCode:    200,