TST: Test failure on 32bit for TestSparseGroupBy.test_aggfuncs
The `test_aggfuncs` test in `/sparse/test_groupby.py` is failing on 32bit: https://travis-ci.org/MacPython/pandas-wheels/jobs/451706570#L5281

Specifically, the pytest output:
```
_______________________ TestSparseGroupBy.test_aggfuncs ________________________
self = <pandas.tests.sparse.test_groupby.TestSparseGroupBy object at 0xde3f08ec>
    def test_aggfuncs(self):
        sparse_grouped = self.sparse.groupby('A')
        dense_grouped = self.dense.groupby('A')
    
        result = sparse_grouped.mean().to_sparse()
        expected = dense_grouped.mean().to_sparse()
    
>       tm.assert_frame_equal(result, expected)
/venv/lib/python3.6/site-packages/pandas/tests/sparse/test_groupby.py:50: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/venv/lib/python3.6/site-packages/pandas/util/testing.py:1185: in assert_extension_array_equal
    assert_numpy_array_equal(left_valid, right_valid)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
left = array([-0.17387645482451206, 0.3414148016424936], dtype=object)
right = array([-0.17387645482451206, 0.3414148016424937], dtype=object)
err_msg = None
    def _raise(left, right, err_msg):
        if err_msg is None:
            if left.shape != right.shape:
                raise_assert_detail(obj, '{obj} shapes are different'
                                    .format(obj=obj), left.shape, right.shape)
    
            diff = 0
            for l, r in zip(left, right):
                # count up differences
                if not array_equivalent(l, r, strict_nan=strict_nan):
                    diff += 1
    
            diff = diff * 100.0 / left.size
            msg = '{obj} values are different ({pct} %)'.format(
                obj=obj, pct=np.round(diff, 5))
>           raise_assert_detail(obj, msg, left, right)
E           AssertionError: numpy array are different
E           
E           numpy array values are different (50.0 %)
E           [left]:  [-0.17387645482451206, 0.3414148016424936]
E           [right]: [-0.17387645482451206, 0.3414148016424937]
/venv/lib/python3.6/site-packages/pandas/util/testing.py:1146: AssertionError
```

The test in question:
https://github.com/pandas-dev/pandas/blob/efd1844daaadee29a57943597431611d554b6c4a/pandas/tests/sparse/test_groupby.py#L43-L48

xref #23318 : it looks like this is the pr that caused the change?

cc : @jreback  @TomAugspurger @5hirish 