`prepend` getting prepended even if it already exists in the ancestors chain
module M; end class A; prepend M; end class B < A; prepend M; end B.ancestors # => [M, B, M, A, Object, Kernel, BasicObject]
Even though I find this behaviour to be more intuitive, it is inconsistent with
Module#include and is potentially breaking.
I didn't see a mention on the [release notes] and the [documentation] is now outdated.