BUG: Handling columns from index_col in _is_potential_multi_index
- [x] closes #33476
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [] whatsnew entry

Hello @mproszewska! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:







There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2020-06-01 00:42:28 UTC I added requested changes.
 Everything should be fine now thanks @mproszewska  @mproszewska , thanks very much!

But @mproszewska , @jreback , should we add an argument to [this line](https://github.com/pandas-dev/pandas/blob/c71bfc36211b5e2d860a06d8fbef902b757bd6e4/pandas/io/parsers.py#L1601), too, shouldn't we?
https://github.com/pandas-dev/pandas/blob/c71bfc36211b5e2d860a06d8fbef902b757bd6e4/pandas/io/parsers.py#L1601