Assign tasks when they are not assigned.

[Ladsgroup]

This will fix https://phabricator.wikimedia.org/T131997

[halfak]

This is probably not what we want. See farther down in that query. I think we want to change the following from

              LEFT JOIN label ON
                  label.task_id = task.id
              [...]
              HAVING
                  COUNT(label.task_id) < campaign.labels_per_task AND
                  SUM((label.user_id IS NOT NULL AND
                       label.user_id = %(user_id)s)::int) = 0

to

              LEFT JOIN workset ON
                  workset.id = workset_task.id
              [...]
              HAVING
                  COUNT(workset_task.task_id) < campaign.labels_per_task AND
                  SUM((workset.user_id IS NOT NULL AND
                       workset.user_id = %(user_id)s)::int) = 0

And drop the AND workset_task.task_id IS NULL because the task could be assigned multiple times in the case that campaign.labels_per_task is > 1.

[Ladsgroup]

I fixed it now :)

[halfak]

I think this should be workset.user_id since we want to check to see if this user was already assigned this task or not. You'll need to join on "workset" as well here.

[halfak]

I just amended a change that addressed my last comment. @Ladsgroup, please review.

[halfak]

Oh! Also, I tested this by running /utility load_schema --reload-test-data and then working through the Article Notability campaign.