(Report as requested by @epriestley on IRC)
I have a workboard which contains three open tasks:
* `T1` has no tasks listed under "Blocked By";
* `T2` has an open task listed under "Blocked By";
* `T3` has a resolved task listed under "Blocked By".
I select "Custom Filter", and choose "Show Tasks Not Blocked By Other Tasks" from the "Blocked" select box.
The workboard now only shows `T1`.
I expect the workboard to show `T1`, because that task cannot be blocked, and I also expect the workboard to show `T2`, because that task's blocking task has been closed, and hence `T2` is no longer blocked from completion.