set eval(engine="python") for python2
see issue https://github.com/pandas-dev/pandas/issues/26549

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Hello @shouldsee! 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 2019-06-07 14:39:32 UTC > this would require a release of the 24.x series. This is not contemplated at the current time. Further I am not even sure this is a good change, what is the reason?

Bascially `eval(engine="numexpr")` is broken on python2-pandas

To reproduce with Python 2.7.12

```python
## !pip2 install numexpr==2.6.9 --user
import pandas as pd
dfc = pd.DataFrame(map(str,range(10)),columns=['colA'])
dfc.query('colA.str.contains("0")',engine="numexpr")
``` > Bascially eval(engine="numexpr") is broken on python2-pandas

and python 2 is no longer supported. So I am not completely objecting to merging this (though it would require some tests / note and such). But pointing out that a release may not be happening for far in the future. > > Bascially eval(engine="numexpr") is broken on python2-pandas
> 
> and python 2 is not longer supported. So I am not completely objecting to merging this (though it would require some tests / note and such). But pointing out that a release may not be happening for far in the future.

Thanks for explaining this to me. I don't care too much about the release, just wanting to make people aware that this bug exists and there are ways to circumventing it so that they don't have to repeat my frustrating debugging practice :smiley: . ok as we have no plans for further PY2 support, closing.