rails/arel — pull request #320 by jsanders (2014-09-26 22:57:38+00:00)
Title: Make union/except/intersect chainable as SelectManager

Fixes #118.

This is the same as #239, but against master instead of 4-0-stable. It would be really nice to get this in so we don't need to keep freshening it! Or if there's a reason it isn't being merged, feedback would be great.