Mozlint used to exit gracefully on a KeyboardInterrupt, but now it seems that the process hangs. Not sure when this stopped working, need to investigate and fix this (and write a test).
I've seen this occasionally when running ESLint. Although I think it might be a matter of timing - doing it at the wrong time hangs, but sometimes I can ctrl-c just fine.
Hm yeah, it does seem to be exiting gracefully now.. though flake8 does take awhile (~5-10 seconds) to clean up after itself. When I filed this I was definitely seeing tracebacks on Ctrl-C though, which shouldn't be happening. I guess I'll leave this open for now, maybe we'll run into it again and find reliable STR.