Fix cache path issue

Author: stephane-caron

robot_descriptions/_cache.py

@@ -130,7 +130,10 @@ def clone_to_cache(description_name: str, commit: Optional[str] = None) -> str:
 
     cache_path = repository.cache_path
     if commit is not None:
-        cache_path += f"-{commit}"
+        # Requirement: the last directory in the cache path is named after the
+        # cache path (more precisely the package name) so that package:// URIs
+        # work in frameworks that resolve them via directories
+        cache_path = f"{cache_path}-{commit}/{cache_path}"
     target_dir = os.path.join(cache_dir, cache_path)
     clone = clone_to_directory(
         repository.url,