Comments should be removed before line continuations, otherwise
the semantics of an assignment change.
Found this during reconversion of qtimageformats.
Adjust test to specifically test for all the expected values.
Amends 76f5b784ce.
Change-Id: Iaa46bbc9cbd7b2390fe9b5f0078ac33d225a9258
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>