I tested this by moving files from my harddrive to a flash drive

LGTM

I wonder if we could test this with a virtual disk image. (I'm thinking something similar to how mac apps a distributed, like a .dmg file) Or we could maybe use docker.

Docker might be a good idea regardless, I've definitely had some "works on my machine" glitches with shelljs.

Huh? Are we talking about the same thing? This was supposed to be about a bug involving the mv command across disk partitions, not about how we distribute the software.

@nfischer: Yeah. I was thinking that a virtual dist and/or a VMish (like Docker) might work to simulate that for testing.

Is there a simple easy to set that up? This is a pretty obscure edge case. I'd rather not mess with docker as a dev dependency for something like this.

Probably not... Let's forget that for now.

Ok, I'll go ahead and merge this unless there's any objections