BUG: fix `-u` and `-i 0` clash
BUG: fix `-u` and `-i 0` clash

mnicholl/MOSFiT,guillochon/FriendlyFit,villrv/MOSFiT,mnicholl/MOSFiT,bmockler/MOSFiT,guillochon/MOSFiT,bmockler/MOSFiT,villrv/MOSFiT,mnicholl/MOSFiT,guillochon/MOSFiT,guillochon/MOSFiT