Don't compute a nonsensical assigned task count for logged-out users
When a logged-out user views the home page, we currently compute a meaningless "assigned tasks" count which just counts every open task. Don't do this.
Ideally ManiphestTaskQuery should get some tightening up too (that is, withOwners(array(null)) should not select every task), but that might affect other stuff and the performance implications of counting every open task are affecting WMF, so just fix the immediate issue for now.
- Viewed homepage as a logged out user, no assigned task count.
- Viewed homepage as a logged-in user, still saw assigned task count.
Reviewers: btrahan, chad, chasemp
Reviewed By: chasemp
Subscribers: 20after4, epriestley
Differential Revision: https://secure.phabricator.com/D10876