Having paragui-1.0 installed portage suggests updating to 1.1. However this breaks moagg because it does not support paragui 1.1 yet. I set the SLOT variable of paragui-1.1.(17) to "1.1" and everything was fine after emerging.
IIRC this just can't be slotted as it has file collisions. No metadata, going to maintainer-needed.
Fix moagg instead.