Files are compiled on startup

[axelson]

I'm not sure why, but I see that some files are recompiled whenever I run heroku run iex -S mix, and I believe it's happening on dyno boot as well. I think this sometimes causes my dynos to not bind to $PORT within 60 seconds.

I am using always_rebuild=false which is probably related. I could switch to always_rebuild=true but that is just a workaround.