TST: troubleshot numexpr test
seemingly unrelated test failure to changes in PR #26662

https://dev.azure.com/pandas-dev/pandas/_build/results?buildId=12414

```
_______ TestAlignment.test_basic_series_frame_alignment[numexpr-python] ________
[gw0] linux -- Python 3.6.8 /home/vsts/miniconda3/envs/pandas-dev/bin/python

self = <pandas.tests.computation.test_eval.TestAlignment object at 0x7f5f831aa5c0>
engine = 'numexpr', parser = 'python'

    def test_basic_series_frame_alignment(self, engine, parser):
        def testit(r_idx_type, c_idx_type, index_name):
            df = mkdf(10, 7, data_gen_f=f, r_idx_type=r_idx_type,
                      c_idx_type=c_idx_type)
            index = getattr(df, index_name)
            s = Series(np.random.randn(5), index[:5])
            if should_warn(s.index, df.index):
                with tm.assert_produces_warning(RuntimeWarning):
                    res = pd.eval('s + df', engine=engine, parser=parser)
            else:
                res = pd.eval('s + df', engine=engine, parser=parser)
    
            if r_idx_type == 'dt' or c_idx_type == 'dt':
                expected = df.add(s) if engine == 'numexpr' else s + df
            else:
                expected = s + df
            assert_frame_equal(res, expected)
    
        # only test dt with dt, otherwise weird joins result
        args = product(['i', 'u', 's'], ['i', 'u', 's'], ('index', 'columns'))
        with warnings.catch_warnings(record=True):
            # avoid warning about comparing strings and ints
            warnings.simplefilter("ignore", RuntimeWarning)
    
            for r_idx_type, c_idx_type, index_name in args:
>               testit(r_idx_type, c_idx_type, index_name)

pandas/tests/computation/test_eval.py:934: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
pandas/tests/computation/test_eval.py:925: in testit
    assert_frame_equal(res, expected)
pandas/_libs/testing.pyx:65: in pandas._libs.testing.assert_almost_equal
    cpdef assert_almost_equal(a, b,
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

>   raise_assert_detail(obj, msg, lobj, robj)
E   AssertionError: DataFrame.columns are different
E   
E   DataFrame.columns values are different (100.0 %)
E   [left]:  Index([           0,            1,            2,            3,            4,
E          '0בקבנ899זק', '28ףן4כנךטש', '63צגהק5שץן', '7סף4נלדקסב', 'אגןנםצככד0',
E          'וכ2ףזאמאןא', 'ל8לצאןחצךר'],
E         dtype='object')
E   [right]: Index(['0בקבנ899זק', '28ףן4כנךטש', '63צגהק5שץן', '7סף4נלדקסב', 'אגןנםצככד0',
E          'וכ2ףזאמאןא', 'ל8לצאןחצךר',            0,            1,            2,
E                     3,            4],
E         dtype='object')

pandas/_libs/testing.pyx:178: AssertionError
```