fix(http1): try to drain connection buffer if user drops Body

src/proto/h1/conn.rs

@@ -655,6 +655,20 @@ where
         }
     }
 
+    /// If the read side can be cheaply drained, do so. Otherwise, close.
+    pub(super) fn poll_drain_or_close_read(&mut self, cx: &mut task::Context<'_>) {
+        let _ = self.poll_read_body(cx);
+
+        // If still in Reading::Body, just give up
+        match self.state.reading {
+            Reading::Init | Reading::KeepAlive => {
+                trace!("body drained");
+                return;
+            }
+            _ => self.close_read(),
+        }
+    }
+
     pub fn close_read(&mut self) {
         self.state.close_read();
     }

src/proto/h1/dispatch.rs

@@ -186,9 +186,9 @@ where
                         Poll::Ready(Err(_canceled)) => {
                             // user doesn't care about the body
                             // so we should stop reading
-                            trace!("body receiver dropped before eof, closing");
-                            self.conn.close_read();
-                            return Poll::Ready(Ok(()));
+                            trace!("body receiver dropped before eof, draining or closing");
+                            self.conn.poll_drain_or_close_read(cx);
+                            continue;
                         }
                     }
                     match self.conn.poll_read_body(cx) {