ERR: better error message on unparseable datetimes
- [ ] closes #10720
- [ ] tests added / passed
- [x] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
Hello @baevpetr! 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 2020-01-21 11:51:47 UTC So, Linux py36_minimum_versions & macOS py36_macos builds do not pass the test:
their exceptions don't seem to contain the passing date. @baevpetr can you continue pushing to #30711 instead of opening a new PR.
 @simonjayhawkins, no, I can't. Sorry.
![image](https://user-images.githubusercontent.com/16845495/72663646-09fcd200-3a06-11ea-9be3-4b07d8053be6.png)
 If you now unable to reinstate the original repository, then you should put a note in the original PR to make the reviewers of the original PR aware. To help maintain the history, should also update the OP to reference the previous PR. And suddenly `pip-20` problems with installation in CI...
Was released several hours ago. @baevpetr is this still active? Can you try to get CI green? Closing as stale but ping if you'd like to pick back up