Pick up new code, add change log

CHANGES.rst

@@ -14,6 +14,10 @@ Release Notes
   correctly with the ``math_util`` module and add unnecessary
   complication. [#265]
 
+- Setting ``export DISABLE_SPHR_GEOM_C_UFUNCS=true`` in your shell environment
+  now disables using ``math_util`` C-extension even when it is available.
+  This is useful for development and debugging. [#268]
+
 
 1.3.1 (5-November-2023)
 =======================

spherical_geometry/tests/test_union.py

@@ -13,14 +13,9 @@
 from numpy.testing import assert_array_almost_equal
 
 # LOCAL
-from spherical_geometry import polygon
+from spherical_geometry import polygon, HAS_C_UFUNCS
 from spherical_geometry.tests.helpers import ROOT_DIR, resolve_imagename
 
-try:
-    from spherical_geometry import math_util
-except ImportError:
-    math_util = None
-
 GRAPH_MODE = False
 
 
@@ -332,7 +327,7 @@ def test_edge_crossings():
 
 
 @pytest.mark.skipif(
-    math_util is None,
+    not HAS_C_UFUNCS,
     reason="math_util C-ext is missing, double accuracy leads to crash"
 )
 def test_almost_identical_polygons_multi_union():