Weird formatting for hanging binop and curried function

[JohnnyMorganz]

function foo()
  return fooooooooooooooooooo(barrr) or fooooooooooooooooooo(barrrrrrrrrrrrrr)(
    hello
  ) or bazzzzzzzzzzzzzzzzzz
end

... should be formatted as ...

function foo()
  return fooooooooooooooooooo(barrr)
    or fooooooooooooooooooo(barrrrrrrrrrrrrr)(hello)
    or bazzzzzzzzzzzzzzzzzz
end

This is at 80 column width, with indent width set to 2. Note, if indent width is set to 4, this formats as expected.

[JohnnyMorganz]

The issue here is actually to do with the formatting tactics for return, not the hanging formatter.
If we replace return with xxxx = (same width), then it formats as expect.