I asked a [python 3 question](https://codereview.stackexchange.com/questions/159186/counting-increasing-subsequences-with-a-hackers-binary-index-tree/159214), and tagged it `python-3.x`. The highlighting was [messed up](https://cloud.githubusercontent.com/assets/12179121/24441389/a1d41f70-1416-11e7-8cc6-5f9db53b0862.png), because the `python-3.x` tag wasn't passing the `lang-py` argument to the JS script that handles the syntax highlighting. I submitted this as an [issue](https://github.com/google/code-prettify/issues/482#issuecomment-289981475) on github, but it couldn't be reproduced because a mod had came along and added the `python` tag, which fixes the syntax highlighting. 

TL;DR: If you ask a `python` question but only tag it `python-3.x`, the syntax highlighting gets messed up.