Issue #5551 has been reported by Tsuyoshi Sawada.
Feature #5551: Enumerable#rdrop
Author: Tsuyoshi Sawada
There is Enumerable#drop(n), which drops elements on the left side, but
there is no counterpart for dropping the right side. It will be
convenient if there is Enumerable#rdrop(n) that drops the elements on
the right side.
[1, 2, 3, 4, 5].rdrop(2) # => [1, 2, 3]