Mozilla and IE should adopt similar policies, and not just for SHA1 deprecation, but for other weak security protocols, too. If website A uses much weaker security than website B, they shouldn't be treated equally by the browser.
Reward the ones who embrace stronger security, punish (within reason, and gradually) those who don't.
Firefox Bug 942515 - stop accepting SHA-1-based SSL certificates with notBefore >= 2014-03-01 and notAfter >= 2017-01-01, or any SHA-1-based SSL certificates after 2017-01-01
Reward the ones who embrace stronger security, punish (within reason, and gradually) those who don't.