Also looks like the output format for cpplint has changed due to 4330b27

what happens if you change cpplint to accept the C extension? You can just edit the python script and the var _valid_extensions.

I have reverted the entire commit from master and the linter works correctly.
I have also tested before and after 4330b27. Before the commit, things still work. After the commit, it stops working.

I didn't necessarily "triage", but I did a git bisect over all recent commits and this is where things stopped working for me.