fix categorical comparison with missing values

Author: another-green

pandas/core/arrays/categorical.py

@@ -104,9 +104,7 @@ def f(self, other):
 
                 # check for NaN in self
                 mask = (self._codes == -1)
-                if mask.any():
-                    # comparison to missing values NaN leads to False
-                    ret[mask] = False
+                ret[mask] = False
                 return ret
             else:
                 if op == '__eq__':

pandas/tests/arrays/categorical/test_operators.py

@@ -195,7 +195,6 @@ def test_comparison_of_ordered_categorical_with_nan_to_scalar(
 
         cat = Categorical([1, 2, 3, None], categories=[1, 2, 3], ordered=True)
         scalar = 2
-        
         with warnings.catch_warnings():
             warnings.simplefilter("ignore", RuntimeWarning)
             expected = getattr(np.array(cat),
@@ -211,7 +210,6 @@ def test_comparison_of_ordered_categorical_with_nan_to_listlike(
 
         cat = Categorical([1, 2, 3, None], categories=[1, 2, 3], ordered=True)
         other = Categorical([2, 2, 2, 2], categories=[1, 2, 3], ordered=True)
-        
         with warnings.catch_warnings():
             warnings.simplefilter("ignore", RuntimeWarning)
             expected = getattr(np.array(cat), compare_operators_no_eq_ne)(2)