Fix race condition in repo renaming (#3418)

models/repo.go

@@ -1579,7 +1579,12 @@ func ChangeRepositoryName(u *User, oldRepoName, newRepoName string) (err error)
 		return fmt.Errorf("GetRepositoryByName: %v", err)
 	}
 
-	// Change repository directory name.
+	// Change repository directory name. We must lock the local copy of the
+	// repo so that we can atomically rename the repo path and updates the
+	// local copy's origin accordingly.
+	repoWorkingPool.CheckIn(com.ToStr(repo.ID))
+	defer repoWorkingPool.CheckOut(com.ToStr(repo.ID))
+
 	newRepoPath := RepoPath(u.Name, newRepoName)
 	if err = os.Rename(repo.RepoPath(), newRepoPath); err != nil {
 		return fmt.Errorf("rename repository directory: %v", err)