Solved desing problem with to_datetime when "ignore" error was being used.
- [x] closes #28120
- [x] tests added / passed `test_to_datetime_some_invalid_numbers`
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] Now when u use some array of integers on to_datetime function passing as arguments: error="ignore" and format="%Y%m%d" it only skips none fitting values instead of all the values.

Hello @IngErnestoAlvarez! 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 2020-12-23 04:52:10 UTC @arw2019  Hi! I leave the code here, with the changes you recommend me to do. I thought it was an open issue, not necessarily a bug, but a feature that can be good for it to be used. What I would understand at first, seeing this, `to_datetime(dt_col, format='%Y%m%d', errors='ignore')`, is that it will transform the array to datetime omitting all the errors and exceptions. It doesn't sound like "if I found an error I won't change anything". But I understand if you see it differently. Thank you for the feedback! I'm not done yet, but It seems that in one Travis build conda had an error "solving the environment", it just gets stuck, it's something I should be worried about? Or first I finish what I'm doing and then take care of that? ignore travis as it's being worked elsewhere (though certainly would appreciate help in that - we r trying to move off it) What u r trying to do? Changing the CI environment? 
What things do u need help with? Maybe I can help so this build: https://travis-ci.org/github/pandas-dev/pandas/jobs/751146161

something changed very recently like in last day or so - and now conda solve time blows up

so we want to fix the install env for just this build to make it work

independent we are working on moving these builds to azure / but that's slightly orthongoal  This pull request is stale because it has been open for thirty days with no activity. Please update or respond to this comment if you're still interested in working on this. closing as stale. if you want to continue, pls ping and can re-open.