Issue: middle mouse click on a link in Firefox, nothing happens.
Expected behavior: middle mouse click on a link, open in new browser tab.
Live example: http://twitter.github.com/bootstrap/

Tested on Win7/Firefox19 Safemode/Non-Safemode failed. IE9/Chrome25 ok.
Notice it when I upgrade to bootstrap v2.3.1.
Switch back to v2.3 and the middle button works again.