Fix mirror error when mirror repo is empty (#30432) (#30467)

Backport #30432
Fix https://github.com/go-gitea/gitea/issues/30424

ps: convert `gitrepo.OpenRepository` to `git.OpenRepository`
remove `ctx` from `checkAndUpdateEmptyRepository`

Co-authored-by: Giteabot <teabot@gitea.io>

services/mirror/mirror_pull.go

@@ -449,19 +449,17 @@ func SyncPullMirror(ctx context.Context, repoID int64) bool {
 		return false
 	}
 
-	var gitRepo *git.Repository
-	if len(results) == 0 {
-		log.Trace("SyncMirrors [repo: %-v]: no branches updated", m.Repo)
-	} else {
-		log.Trace("SyncMirrors [repo: %-v]: %d branches updated", m.Repo, len(results))
-		gitRepo, err = git.OpenRepository(ctx, m.Repo.RepoPath())
-		if err != nil {
-			log.Error("SyncMirrors [repo: %-v]: unable to OpenRepository: %v", m.Repo, err)
-			return false
-		}
-		defer gitRepo.Close()
+	gitRepo, err := git.OpenRepository(ctx, m.Repo.RepoPath())
+	if err != nil {
+		log.Error("SyncMirrors [repo: %-v]: unable to OpenRepository: %v", m.Repo, err)
+		return false
+	}
+	defer gitRepo.Close()
 
+	log.Trace("SyncMirrors [repo: %-v]: %d branches updated", m.Repo, len(results))
+	if len(results) > 0 {
 		if ok := checkAndUpdateEmptyRepository(m, gitRepo, results); !ok {
+			log.Error("SyncMirrors [repo: %-v]: checkAndUpdateEmptyRepository: %v", m.Repo, err)
 			return false
 		}
 	}
@@ -533,16 +531,24 @@ func SyncPullMirror(ctx context.Context, repoID int64) bool {
 	}
 	log.Trace("SyncMirrors [repo: %-v]: done notifying updated branches/tags - now updating last commit time", m.Repo)
 
-	// Get latest commit date and update to current repository updated time
-	commitDate, err := git.GetLatestCommitTime(ctx, m.Repo.RepoPath())
+	isEmpty, err := gitRepo.IsEmpty()
 	if err != nil {
-		log.Error("SyncMirrors [repo: %-v]: unable to GetLatestCommitDate: %v", m.Repo, err)
+		log.Error("SyncMirrors [repo: %-v]: unable to check empty git repo: %v", m.Repo, err)
 		return false
 	}
+	if !isEmpty {
+		// Get latest commit date and update to current repository updated time
+		commitDate, err := git.GetLatestCommitTime(ctx, m.Repo.RepoPath())
+		if err != nil {
+			log.Error("SyncMirrors [repo: %-v]: unable to GetLatestCommitDate: %v", m.Repo, err)
+			return false
+		}
+
+		if err = repo_model.UpdateRepositoryUpdatedTime(ctx, m.RepoID, commitDate); err != nil {
+			log.Error("SyncMirrors [repo: %-v]: unable to update repository 'updated_unix': %v", m.Repo, err)
+			return false
+		}
 
-	if err = repo_model.UpdateRepositoryUpdatedTime(ctx, m.RepoID, commitDate); err != nil {
-		log.Error("SyncMirrors [repo: %-v]: unable to update repository 'updated_unix': %v", m.Repo, err)
-		return false
 	}
 
 	log.Trace("SyncMirrors [repo: %-v]: Successfully updated", m.Repo)