fix error reported by go vet

importer/importer.go

@@ -140,7 +140,7 @@ func (im *Importer) runWorker(idx int) {
 		select {
 		case req := <-im.workerChan:
 			if req.ctx.isCanceled() {
-				im.dbgLog.Printf("importer: worker %d got canceled request")
+				im.dbgLog.Printf("importer: worker %d got canceled request", idx)
 				continue
 			}
 			req.enqueuedChan <- true