fix 'go vet' warnings

pkg/registry/minion/healthy_registry.go

@@ -81,7 +81,7 @@ func (r *HealthyRegistry) ListMinions(ctx api.Context) (currentMinions *api.Mini
 		if status == health.Healthy {
 			result.Items = append(result.Items, minion)
 		} else {
-			glog.Errorf("%s failed a health check, ignoring.", minion)
+			glog.Errorf("%#v failed a health check, ignoring.", minion)
 		}
 	}
 	return result, nil

pkg/registry/minion/rest_test.go

@@ -152,7 +152,7 @@ func TestMinionStorageValidUpdate(t *testing.T) {
 		"baz": "home",
 	}
 	if _, err = storage.Update(ctx, minion); err != nil {
-		t.Error("Unexpected error: %v", err)
+		t.Errorf("Unexpected error: %v", err)
 	}
 }