more ruby parser brittleness

gistfile1.rb

def this_is_okay
  {
    :a => "b"
  }
end

def this_is_too
  yield ({
    :a => "b"
  })
end

def this_is_not
  yield {
    :a => "b"
  }
end
# wat.rb:14: syntax error, unexpected '{'
# wat.rb:16: syntax error, unexpected '}', expecting keyword_end