BUG: how do we perform pandas series comparison based on level?
I have a multi-index dataframe `y_test`:

    blockNumber_base10@coarsegrained#1024  address_idx
    9441280                                2             -0.012421
                                           3              0.001400
                                           6             -0.012696
                                           7              0.003558
                                           15             0.003649
                                                            ...   
    9854976                                935783         0.000000
                                           935785         0.000000
                                           935786         0.000000
                                           935788         0.000000
                                           935789         0.000000
    Name: price@fwd#001024@div#price#m1, Length: 1146272, dtype: float64


We want to compare with groupby min. 


    y_test_tmp  = y_test.groupby(level = 0).quantile(0.8)

    blockNumber_base10@coarsegrained#1024
    9441280    0.005130
    9442304    0.000973
    9443328    0.000461
    9444352    0.001354
    9445376    0.000921
                 ...   
    9850880    0.000552
    9851904    0.000953
    9852928    0.000591
    9853952    0.000000
    9854976    0.000000
    Name: price@fwd#001024@div#price#m1, Length: 405, dtype: float64


I want to compare with them based on `blockNumber_base10@coarsegrained#1024`, so i wanted to compute  `y_test > y_test_tmp`. But I got this error:

    ---------------------------------------------------------------------------
    ValueError                                Traceback (most recent call last)
    <ipython-input-318-ad2813982941> in <module>
    ----> 1 y_test > y_test_tmp
    
    ~/anaconda3/lib/python3.8/site-packages/pandas/core/ops/common.py in new_method(self, other)
         63         other = item_from_zerodim(other)
         64 
    ---> 65         return method(self, other)
         66 
         67     return new_method
    
    ~/anaconda3/lib/python3.8/site-packages/pandas/core/arraylike.py in __gt__(self, other)
         43     @unpack_zerodim_and_defer("__gt__")
         44     def __gt__(self, other):
    ---> 45         return self._cmp_method(other, operator.gt)
         46 
         47     @unpack_zerodim_and_defer("__ge__")
    
    ~/anaconda3/lib/python3.8/site-packages/pandas/core/series.py in _cmp_method(self, other, op)
       4971 
       4972         if isinstance(other, Series) and not self._indexed_same(other):
    -> 4973             raise ValueError("Can only compare identically-labeled Series objects")
       4974 
       4975         lvalues = extract_array(self, extract_numpy=True)
    
    ValueError: Can only compare identically-labeled Series objects

Any suggestion? Thanks!
