(maybe) delete /tmp

[tych0]

If a user has modified /tmp, surely they don't expect these files to persist. Maybe we should delete everything in /tmp before generating a layer (or really, just ignore /tmp; that would have to live in the umoci/squashtool API though).

Thoughts?

[smoser]

hm.m. its similar to the request i had for "output-only" but in reverse. I wanted to have it collect only certain directories, you're saying to clean certain directories.

I'm tempted to say "you should make that an option". But I think its probably better and simpler to just do it (remove all files in /tmp and even /run) and then if someone complains you can address their desire.