[test only] safe.directory not global on repository unittest

pkg/testing/testing.go

@@ -145,9 +145,10 @@ func ServeRepo(name string, t *testing.T) string {
 	)
 	// This is to prevent "fatal: detected dubious ownership in repository at <source_reposutory_path>" while executing
 	// unit tests on other environments (such as Prow CI)
-	cmd := exec.Command("git", "config", "--global", "--add", "safe.directory", abs)
-	_, err := cmd.CombinedOutput()
+	cmd := exec.Command("git", "config", "--add", "safe.directory", abs)
+	o, err := cmd.CombinedOutput()
 	if err != nil {
+		t.Log("error adding safe.directory ", string(o))
 		t.Fatal(err)
 	}
 	return fmt.Sprintf("%v/%v", url, repo)