Make guard before io creation when requiring new connection poll

actix-http/src/client/pool.rs

@@ -126,13 +126,12 @@ where
                     ))
                 }
                 Acquire::Available => {
+                    let guard = OpenGuard::new(key, inner);
                     // open tcp connection
                     let (io, proto) = connector.call(req).await?;
 
                     let config = inner.borrow().config.clone();
 
-                    let guard = OpenGuard::new(key, inner);
-
                     if proto == Protocol::Http1 {
                         Ok(IoConnection::new(
                             ConnectionType::H1(io),