re-enable server http upgrades

Author: seanmonstar

src/server/conn.rs

@@ -992,7 +992,6 @@ mod upgrades {
                 match ready!(Pin::new(self.inner.conn.as_mut().unwrap()).poll(cx)) {
                     Ok(proto::Dispatched::Shutdown) => return Poll::Ready(Ok(())),
                     Ok(proto::Dispatched::Upgrade(pending)) => {
-                        unimplemented!("Upgraded pending!");
                         let h1 = match mem::replace(&mut self.inner.conn, None) {
                             Some(Either::A(h1)) => h1,
                             _ => unreachable!("Upgrade expects h1"),