Fix isempty detection of git repository (#18746)

* Fix isempty detection of git repository

* Fix IsEmpty check

Author: lunny

modules/git/repo.go

@@ -80,21 +80,20 @@ func InitRepository(ctx context.Context, repoPath string, bare bool) error {
 // IsEmpty Check if repository is empty.
 func (repo *Repository) IsEmpty() (bool, error) {
 	var errbuf, output strings.Builder
-	if err := NewCommand(repo.Ctx, "rev-list", "--all", "--count", "--max-count=1").
+	if err := NewCommand(repo.Ctx, "show-ref", "--head", "^HEAD$").
 		RunWithContext(&RunContext{
 			Timeout: -1,
 			Dir:     repo.Path,
 			Stdout:  &output,
 			Stderr:  &errbuf,
 		}); err != nil {
+		if err.Error() == "exit status 1" && errbuf.String() == "" {
+			return true, nil
+		}
 		return true, fmt.Errorf("check empty: %v - %s", err, errbuf.String())
 	}
 
-	c, err := strconv.Atoi(strings.TrimSpace(output.String()))
-	if err != nil {
-		return true, fmt.Errorf("check empty: convert %s to count failed: %v", output.String(), err)
-	}
-	return c == 0, nil
+	return strings.TrimSpace(output.String()) == "", nil
 }
 
 // CloneRepoOptions options when clone a repository