Thanks, today I noticed the same problem after switching to the Ionic 2 CLI, this solution works!
Previously I used another workaround but it was only a half solution, and I ran into a few other issues with the Ionic 2 CLI as well:
Which Ionic CLI to use? 1.7.16 or 2.0.0.xxx beta?
All in all the upgrade from Ionic CLI 1 to 2 (for running/building Ionic 1 projects) was a bit less smooth and easy than I expected.