scala/scala — pull request #1071 by rklaehn (2012-08-06 22:22:19+00:00)
Title: Prevent creation of one element HashSetCollision1

if there is one element, there is no collision!

A problem with this might be that size for ListSet is O(N), and there is no other way to figure out if a ListSet contains exactly one element. Also, head might not be efficient for ListSet.

But clearly having a HashSetCollision1 with one element is undesirable.