1. Go to a task, i.e. https://secure.phabricator.com/T4446
2. Click to a project link, i.e. https://secure.phabricator.com/tag/wikimedia/
3. Click on the "Workboards" link.

EXPECTED

The link points to the workboard, i.e. https://secure.phabricator.com/project/board/404/

ACTUALLY

The link is broken and points to i.e. https://secure.phabricator.com/project/board//

Note that the link works properly in the visually equivalent project page, https://secure.phabricator.com/project/view/404/