Possibility to compile styles without px fallback in production mode

At variables.scss http://cgit.drupalcode.org/zen/tree/STARTERKIT/components/init/_variable... we have

// px fallbacks for rem units are needed for IE 8 and earlier.
$rem-fallback:      false;

During development it always `true`. Is there a way to compile styles for production mode with keeping this fallback as false (even if it was overrided to true at variables.scss file)? From gulpfile it can be useful feature