Started seeing this on master: <img width="285" alt="screen shot 2017-05-11 at 6 17 51 pm" src="https://cloud.githubusercontent.com/assets/810438/25962591/38f95a2e-3676-11e7-89fa-e73449844264.png"> I get this when I revert https://github.com/facebookincubator/create-react-app/pull/1842/commits/04dcef1a50e9843e333419a2abd6ab19621a7b83 and try to cause some React warnings.
