Support Tee() in the ReadFrom case as well

web/util/writer_proxy.go

@@ -104,6 +104,9 @@ func (f *fancyWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
 	return hj.Hijack()
 }
 func (f *fancyWriter) ReadFrom(r io.Reader) (int64, error) {
+	if f.basicWriter.tee != nil {
+		return io.Copy(&f.basicWriter, r)
+	}
 	rf := f.basicWriter.ResponseWriter.(io.ReaderFrom)
 	f.basicWriter.maybeWriteHeader()
 	return rf.ReadFrom(r)