make conftest._cython_table deterministic for Python<3.6

Author: topper-123

pandas/conftest.py

@@ -123,10 +123,11 @@ def all_arithmetic_operators(request):
     return request.param
 
 
-# use sorted as dicts in py<3.6 have random order, which xdist doesn't like
-_cython_table = sorted(((key, value) for key, value in
-                        pd.core.base.SelectionMixin._cython_table.items()),
-                       key=lambda x: x[0].__name__)
+# manual sorting as dicts in py<3.6 have random order, which xdist doesn't like
+_cython_table = [(key, pd.core.base.SelectionMixin._cython_table[key]) for key
+                 in [sum, max, min,
+                     np.all, np.any, np.sum, np.mean, np.prod, np.std, np.var,
+                     np.median, np.max, np.min, np.cumprod, np.cumsum]]
 
 
 @pytest.fixture(params=_cython_table)