[ruby-core:107830] [Ruby master Bug#18621] Fiber.yield loses the fact it was kwargs from Fiber#resume

Issue #18621 has been updated by Eregon (Benoit Daloze).


Note that kwargs are correctly passed through for Fiber.new:
```ruby
Fiber.new do |*args, **kwargs|
  p kwargs # => {a: 1}
end.resume(a: 1)
```

----------------------------------------
Bug #18621: Fiber.yield loses the fact it was kwargs from Fiber#resume
https://bugs.ruby-lang.org/issues/18621#change-96758

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
* ruby -v: ruby 3.2.0dev (2022-03-03T08:56:31Z master c1790f8c11) [x86_64-linux]
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: REQUIRED, 3.1: REQUIRED
----------------------------------------
```ruby
f = Fiber.new do
  args = Fiber.yield
  args
end
f.resume
args = f.resume(a: 1)
Hash.ruby2_keywords_hash?(args) # => false, but should be true, isn't it?
```

This also means if there is `foo(*args)` later and `foo` would require kwargs it would fail:

```ruby
def foo(a: 1) = a

f = Fiber.new do
  args = Fiber.yield
  args
end
f.resume
args = f.resume(a: 1)
foo(*args)
# =>
# -:1:in `foo': wrong number of arguments (given 1, expected 0) (ArgumentError)
# 	from -:9:in `<main>'
```

cc @jeremyevans0 @mame



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