all: fix vet errors

It would be nice to run these alongside the tests. There is only one
vet error left in the x/build tree, an unreachable return next to a
TODO.

Change-Id: Ic31d96cdee5bb0f6b9795237ff3b743a4b76e3cf
Reviewed-on: https://go-review.googlesource.com/36898
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/kubernetes/client.go b/kubernetes/client.go
index ded2ab4..a99a5fd 100644
--- a/kubernetes/client.go
+++ b/kubernetes/client.go
@@ -223,7 +223,7 @@
 	body, err := ioutil.ReadAll(res.Body)
 	res.Body.Close()
 	if err != nil {
-		return fmt.Errorf("failed to read response body: DELETE %q: %v, url, err")
+		return fmt.Errorf("failed to read response body: DELETE %q: %v", url, err)
 	}
 	if res.StatusCode != http.StatusOK {
 		return fmt.Errorf("http error: %d DELETE %q: %q: %v", res.StatusCode, url, string(body), err)