Updating pip to 1.5.6 and virtualenv to 1.11.6 should fix the issues (current versions in sid are 1.5.5 and 1.11.4 respectively).
Apologies for not using the bug tracker, too many hoops to jump through. I'd usually just wait it out - sid being sid - but this has been irking me for over a week.
Cheers,
Mario Cruz