To contribute to ansible-lint, please use pull requests on a branch of your own fork.
After creating your fork on github, you can do:
git clone git@github.com:yourname/ansible-lint
cd ansible-lint
git checkout -b your-branch-name
DO SOME CODING HERE
git add your new files
git commit
git push origin your-branch-name
You will then be able to create a pull request from your commit.
All fixes to core functionality (i.e. anything except rules or examples) should be accompanied by tests that fail prior to your change and succeed afterwards.
Feel free to raise issues in the repo if you don't feel able to contribute a code fix.
Although the code is not currently PEP8 compliant, that is an aspiration. Fixes that only adjust PEP8 (especially large scale ones) affect git blame in a bad way, but please feel free to clean up code in areas near where you're working!