scala/scala — pull request #1108 by rklaehn (2012-08-09 20:26:41+00:00)
Title: Ensure that a.merged(b)(null) always chooses a in case of collisions

Fixes bug in bugfix of SI-5879

Moved definition of liftMerger to companion object and replaced null with a default merger so merge works predictably if you pass null as a merger.