rails/arel — pull request #310 by cristianbica (2014-09-05 09:34:02+00:00)
Title: Fixed for nested arrays given to SQL IN

This was reported first at https://github.com/rails/rails/issues/16580 but from my digging it seems it's a behaviour change in arel 6. Not sure if this should be fixed in rails (https://github.com/rails/rails/pull/16805) or in arel.

/cc @tenderlove