bugfix in data file bundling

tests/test_io_handlers.py

@@ -142,11 +142,15 @@ def test_zip_bundle(tmp_path: Path):
     params.freeze()
 
     prop2 = propagation(tmp_path / "file3.zip", params, bundle_data=True)
+    assert prop2.parameters is not params
+    assert prop2.parameters.dispersion_file is not params.dispersion_file
 
-    assert prop2.parameters.dispersion_file.path == new_disp_path.name
-    assert prop2.parameters.dispersion_file.prefix == "zip"
-    assert prop2.parameters.effective_area_file.path == new_aeff_path.name
-    assert prop2.parameters.effective_area_file.prefix == "zip"
+    prop3 = propagation(tmp_path / "file3.zip")
+
+    assert prop3.parameters.dispersion_file.path == new_disp_path.name
+    assert prop3.parameters.dispersion_file.prefix == "zip"
+    assert prop3.parameters.effective_area_file.path == new_aeff_path.name
+    assert prop3.parameters.effective_area_file.prefix == "zip"
 
     with ZipFile(tmp_path / "file3.zip", "r") as zfile:
         with zfile.open(new_aeff_path.name) as file: