Created by: gaearon
Fixes https://github.com/facebook/create-react-app/issues/5140. Fixes https://github.com/facebook/create-react-app/issues/5188.
While unfortunate due to concerns in https://github.com/facebook/create-react-app/issues/5188#issuecomment-425844969, I don't feel comfortable with webpack's default behavior until webpack adds a warning or an error for this (https://github.com/webpack/webpack/issues/6571#issuecomment-425897134). When webpack does, we can reconsider and go with webpack's default behavior.
I checked that this change fixes the reproducing case in https://github.com/cdaringe/will-u-load-my-styl.