headers timeout with response is nil

conn.go

@@ -143,7 +143,7 @@ func (obj *connecotr) taskMain(task *reqTask, waitBody bool) (retry bool) {
 			return false
 		}
 		if task.res == nil {
-			task.err = errors.New("response is nil")
+			task.err = task.ctx.Err()
 			obj.Close()
 			return false
 		}

roundTripper.go

@@ -213,6 +213,9 @@ func (obj *roundTripper) poolRoundTrip(ctxData *reqCtxData, task *reqTask, key s
 		case <-task.emptyPool:
 			return true
 		case <-task.ctx.Done():
+			if task.err==nil{
+				task.err=task.ctx.Err()
+			}
 			return false
 		}
 	default: