Aside from identation, seed should change for each object. Otherwise to objects
with a copied mesh would get the exactly same "random" selection.
And we do so in a consistent way so it doesn't vary depending on
object order.
Seed bump using hash suggested by Campbell Barton and Sergey Sharybin.
Maniphest Tasks: T54643
Differential Revision: https://developer.blender.org/D3231