#3467 fix clone fail when wiki is empty

models/wiki.go

@@ -76,7 +76,9 @@ func (repo *Repository) LocalWikiPath() string {
 
 // UpdateLocalWiki makes sure the local copy of repository wiki is up-to-date.
 func (repo *Repository) UpdateLocalWiki() error {
-	return UpdateLocalCopyBranch(repo.WikiPath(), repo.LocalWikiPath(), "master")
+	// Don't pass branch name here because it fails to clone and
+	// checkout to a specific branch when wiki is an empty repository.
+	return UpdateLocalCopyBranch(repo.WikiPath(), repo.LocalWikiPath(), "")
 }
 
 func discardLocalWikiChanges(localPath string) error {