On Master: INTERNAL ERROR: Black produced different code on the second pass of the formatter.

[tommyjcarpenter]

Describe the bug A clear and concise description of what the bug is.

Black itself said: INTERNAL ERROR: Black produced different code on the second pass of the formatter.

To Reproduce Steps to reproduce the behavior:

1. Take this file

from f.index import I
import pandas as pd
from pandas.tseries.holiday import USFederalHolidayCalendar


class Foo(I):
    def __init__(self, id, sec="TY"):
        super().__init__(id)
        self.sec = sec
        if self.sec == "TY":
            self.rebalance_dates = (pd.date_range(start="2001-02-01",
                                       end="2019-09-30",
                                       freq=pd.offsets.CustomBusinessMonthEnd(n=3,
                                                                              calendar=USFederalHolidayCalendar()))
                               - pd.offsets.CustomBusinessDay(2, calendar=USFederalHolidayCalendar()))

2. Run Black on it with these arguments: line-length=120 IE black --line-length 120 fut_black.py
3. See error

error: cannot format fut_black.py: INTERNAL ERROR: Black produced different code on the second pass of the formatter.  Please report a bug on https://github.com/psf/black/issues.

Expected behavior A clear and concise description of what you expected to happen.

it works and does not fail

Environment (please complete the following information):

• Version: [e.g. master] black, version 20.8b1
• OS and Python version: [e.g. Linux/Python 3.7.4rc1] Mac big sur, Python 3.9.1

Does this bug also happen on master? To answer this, you have two options:

YES: https://black.now.sh/?version=master&state=_Td6WFoAAATm1rRGAgAhARYAAAB0L-Wj4AL8AVBdAD2IimZxl1N_WlkPinBFn-cYonV7eCOMygG8rVB4VnmDCouqoBdRV1UuH1GlOkKjrnnM_UPrsADWpdtkn6p7zhnptKkCDeEshX4CR4UYfK04Rt8A40Jd2ZVPmE0pX0tQ4Ihpay5BWB9wVKae4wFyynWuAq3OTiCVooq5xu_OiW1uvoVwkjk31OcLYnxcricdzytnv3PquX4rOFP9WBcz0N8DhrtoC8pMOK-Y0bz_FArDXxKdCj9W_rW72NgZuo4shR3WsfdLqetgpEpfuRTxrAKnlTRQCMU6s5lN8LrS8HSMQyRfWxXCcRLvEE9Q-JqPCPMntqnAgZ7FsYEnrpdESJx_fdDlVYuNylMnhRhWgvOpHuqmAJon-FiAF2yZRcWqQ6eDX8kDVTI0rB3zQjpZZMzCZU1Cpk4J5WFQFh7mFJsNdt2j-lw5Yc2hsUSXGaldAAA5KQgB1ExVXwAB7AL9BQAA1VDUqrHEZ_sCAAAAAARZWg==

1. Use the online formatter at https://black.now.sh/?version=master, which will use the
   latest master branch.

If you dump this file into that online editor, it will complain

[mvolfik]

Likely a duplicate of #1629 , as this file works after applying #1958

[ichard26]

Hello!

All reproduction cases in this issue format without error on master. The fixing commit was 8672af3 from PR GH-2126. I'll be marking this issue as a duplicate of GH-1629 since that's what GH-2126 aimed to fix and it's highly likely this issue falls under GH-1629.

Since we use the issue tracker as a reflection of what's on master, I'll be closing this issue. If you have any issues, especially with the new (but stable) output, please open a new issue. Oh and the fix should be available in a published release soon, see GH-2125 for more info.

Thank you for reporting!