Next Subfolder Struggles

Hey all! I love Next.js + Now, but have identified a bug. This repo is an attempt to reproduce it.

I am currently running now dev on Windows 10. To install:

1. git clone this repo
2. yarn install (or use npm, if you so choose)
3. now dev

I would expect all of the following pages to work, but only some do:

✅ http://localhost:3000/
✅ http://localhost:3000/a
❌ http://localhost:3000/b
❌ http://localhost:3000/a/c

However, in the production Now environment, everything works great! https://next-subfolder-struggles.pulljosh.now.sh/

Thanks to the Zeit team for all their excellent work! :)