Pandas 0.24.0 breaks my pandas dataframe with special column identifiers - pandas

Question

I had code that worked fine until I tried to run it on a coworker's machine, whereupon I discovered that while it worked using pandas 0.22.0, it broke on pandas 0.24.0. For the moment, we've solved this problem by downgrading their copy of pandas, but I would like to find a better solution if one exists.
The problem seems to be that I am creating a user-defined class to use as identifiers for my columns in the dataframe. When trying to compare two dataframes it for some reason tries to call my column labels as functions, and then throws an exception because they aren't callable
Here's some example code:
import pandas as pd
import numpy as np
class label(object):
def __init__(self, var):
self.var = var
def __eq__(self,other):
return self.var == other.var
df = pd.DataFrame(np.eye(5),columns=[label(ii) for ii in range(5)])
df == df
This produces the following stack trace:
Traceback (most recent call last):
File "<ipython-input-4-496e4ab3f9d9>", line 1, in <module>
df==df1
File "C:\...\site-packages\pandas\core\ops.py", line 2098, in f
return dispatch_to_series(self, other, func, str_rep)
File "C:\...\site-packages\pandas\core\ops.py", line 1157, in dispatch_to_series
new_data = expressions.evaluate(column_op, str_rep, left, right)
File "C:\...\site-packages\pandas\core\computation\expressions.py", line 208, in evaluate
return _evaluate(op, op_str, a, b, **eval_kwargs)
File "C:\...\site-packages\pandas\core\computation\expressions.py", line 68, in _evaluate_standard
return op(a, b)
File "C:\...\site-packages\pandas\core\ops.py", line 1135, in column_op
for i in range(len(a.columns))}
File "C:\...\site-packages\pandas\core\ops.py", line 1135, in <dictcomp>
for i in range(len(a.columns))}
File "C:\...\site-packages\pandas\core\ops.py", line 1739, in wrapper
name=res_name).rename(res_name)
File "C:\...\site-packages\pandas\core\series.py", line 3733, in rename
return super(Series, self).rename(index=index, **kwargs)
File "C:\...\site-packages\pandas\core\generic.py", line 1091, in rename
level=level)
File "C:\...\site-packages\pandas\core\internals\managers.py", line 171, in rename_axis
obj.set_axis(axis, _transform_index(self.axes[axis], mapper, level))
File "C:\...\site-packages\pandas\core\internals\managers.py", line 2004, in _transform_index
items = [func(x) for x in index]
TypeError: 'label' object is not callable
I've found I can fix the problem by making my class callable with a single argument and returning that argument, but that breaks .loc indexing, which will default to treating my objects as callables.
This problem only occurs when the custom objects are in the columns - the index can handle them just fine.
Is this a bug or a change in usage, and is there any way I can work around it without giving up my custom labels?