Something very strange is happening with this query:
As @Zache reported, the query runs fine from a labs console,
8011 rows in set (7.12 sec)
However, it hangs forever when run from quarry. The older query above has been in the "running" status for over a month now.
Update: I've changed the query and it runs fine like this, https://quarry.wmflabs.org/query/20200
Leaving this card for anyone who is interested.