For a method such as:
def foo(*callee_args) end
If this method is called with a flagged hash (created by a method
flagged with ruby2_keywords), this previously passed the hash
through without modification. With this change, it acts as if the
last hash was passed as keywords, so a call to:
foo(*caller_args)
where the last element of caller_args is a flagged hash, will be
treated as:
foo(*caller_args[0...-1], **caller_args[-1])
As a result, inside foo, callee_args[-1] is an unflagged duplicate
of caller_args[-1] (all other elements of callee_args match
caller_args).
Fixes [Bug #18625]
752c3dad98