diff --git a/src/apm_cli/cli.py b/src/apm_cli/cli.py
index 56712e238..48dd55e7f 100644
--- a/src/apm_cli/cli.py
+++ b/src/apm_cli/cli.py
@@ -1841,7 +1841,7 @@ def download_callback(dep_ref, modules_dir):
                             _dl_progress.remove_task(_pd_tid)
                             # Silent: sequential loop below will retry and report errors
 
-        _pre_downloaded_keys = set(_pre_download_results.keys())
+        _pre_downloaded_keys = builtins.set(_pre_download_results.keys())
 
         # Create progress display for sequential integration
         with Progress(
diff --git a/src/apm_cli/deps/github_downloader.py b/src/apm_cli/deps/github_downloader.py
index 13189a342..cd90ed0d0 100644
--- a/src/apm_cli/deps/github_downloader.py
+++ b/src/apm_cli/deps/github_downloader.py
@@ -1073,8 +1073,7 @@ def _try_sparse_checkout(self, dep_ref: DependencyReference, temp_clone_path: Pa
                 ['git', 'sparse-checkout', 'set', subdir_path],
             ]
             fetch_cmd = ['git', 'fetch', 'origin']
-            if ref:
-                fetch_cmd.append(ref)
+            fetch_cmd.append(ref or 'HEAD')
             fetch_cmd.append('--depth=1')
             cmds.append(fetch_cmd)
             cmds.append(['git', 'checkout', 'FETCH_HEAD'])