Solved by Flexbox creator here. I wanted to add that if you're using flexbox today, you should also check out this other repo of mine: https://github.com/philipwalton/flexbugs A community-curated list of flexbox issues and cross-browser workarounds for them.
This makes feel the project more interesting, because if I hit one of the already covered problems, I already know where I can (probably) find the solution.