Student PR's - nbdistribute & nbauthor should be able to focus on distributing one assignment at a time or one file?

[lwasser]

I pretended that i was a student. i downloaded week 5. but i don't think i made any purposeful changes. Regardless, when i just pushed week 6, i ended up with a potential conflict where git asked me to change my edits to week 5.

Because this is inherit to github, i think we should manage nbauthor and nbdistribute so that you can push a single assignment at a time. And once that is pushed, you can't update it unless there is some clever way to update something a student is already working on without a conflict. I currently am not sure how to accept the new assignment without stashing or deleting /checking out my work to week 5.