WIP: remove stale code, add whats-new.rst entry

Author: kmuehlbauer

doc/whats-new.rst

@@ -36,6 +36,8 @@ Bug fixes
 ~~~~~~~~~
 - Fix plot.line crash for data of shape ``(1, N)`` in _title_for_slice on format_item (:pull:`5948`).
   By `Sebastian Weigand <https://github.com/s-weigand>`_.
+- Fix a regression in the removal of duplicate backend entrypoints (:issue:`5944`, :pull:`5959`)
+  By `Kai Mühlbauer <https://github.com/kmuehlbauer>`_.
 
 Documentation
 ~~~~~~~~~~~~~
@@ -49,6 +51,10 @@ Documentation
 Internal Changes
 ~~~~~~~~~~~~~~~~
 
+- Use ``importlib`` to replace functionality of ``pkg_resources`` in
+  backend plugins tests. (:pull:`5959`).
+  By `Kai Mühlbauer <https://github.com/kmuehlbauer>`_.
+
 
 .. _whats-new.0.20.1:
 

xarray/tests/test_plugins.py

@@ -49,7 +49,6 @@ def dummy_duplicated_entrypoints():
 
 @pytest.mark.filterwarnings("ignore:Found")
 def test_remove_duplicates(dummy_duplicated_entrypoints) -> None:
-    entrypoints = plugins.remove_duplicates(dummy_duplicated_entrypoints)
     with pytest.warns(RuntimeWarning):
         entrypoints = plugins.remove_duplicates(dummy_duplicated_entrypoints)
     assert len(entrypoints) == 2