fix: only extract an archive if we just downloaded it.

Fixes #195.

src/bob/bio/base/database/utils.py

@@ -599,7 +599,8 @@ def download_file(
                 f"correspond to '{checksum}'."
             )
 
-    if extract:
+    # Extract only if the file was re-downloaded
+    if extract and needs_download:
         local_file = extract_archive(local_file)
 
     return local_file