Creates invalid code when run with the fullPaths option

[Pita]

I created a demo here: https://github.com/Pita/repro-factor-bug-2

run: 1) npm install 2) node build.js 3) node test.js

You can see that the code works fine if you outcomment the fullpaths option

[Pita]

This prevents it from working with watchify

[terinjokes]

factor-bundle has never worked with watchify. We're working on that as part of #26.

[jgoz]

19ab08b50f