fix(client): ensure idle connection is pooled before response body finishes

src/client/conn.rs

@@ -128,6 +128,10 @@ impl<B> SendRequest<B>
         self.dispatch.poll_ready(cx)
     }
 
+    pub(super) fn is_ready(&self) -> bool {
+        self.dispatch.is_ready()
+    }
+
     pub(super) fn is_closed(&self) -> bool {
         self.dispatch.is_closed()
     }