styled-components: Classname ordering problem since 2.1.2

Version

styled-components@2.1.2 babel-plugin-styled-components@1.1.7 (SSR enabled, no preprocessing)

Reproduction / Steps to reproduce

I don’t have repro steps right now, but I’m seeing an issue with the order of how the generated classes are concatenated in v2.1.2, specifically in NODE_ENV=production. Downgrading to v2.1.1 fixes it.

I have a component chain that looks like this:

1. BaseSVG = ({ height, width, ...props }) => <svg {...props} />
2. Icon = styled(BaseSVG)
3. Arrow = Icon.extend.attrs({ viewBox: '0 0 63 40' })
4. StyledArrow = styled(Arrow)

For some reason, the generated class name for #4 is being concatenated before #2.