BUG: Fix sort_values bug that creates unprintable object
- [x] closes #39426 
- [x] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [x] whatsnew entry

The problem occurs when sorting on columns and the `ignore_index` parameter is set to `True`. `sort_values` tries to refit the index after the columns have been sorted resulting in a corrupted dataframe.
Hello @zitorelova! 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 2021-02-03 14:54:59 UTC needs a test precommit is failing precommit is passing now Seems to be a `ResourceWarning` causing one of the checks to fail. Is this related? thanks @zitorelova 