Odd Complex behavior

[Sean McAfee]

> bag i, 2i - i
bag(0+1i(2))

Well and good.

> bag -i, -2i + i
bag(0-1i, -0-1i)

Huh?  But this works as expected:

> bag Complex.new(0, -1), Complex.new(0, -2) + Complex.new(0, 1)
bag(0-1i(2))

Is this a bug, or is there a sense in which it's correct?