fix: prevent infinite loop in rig subset proposals
fix: prevent infinite loop in rig subset proposals

Summary: This Diff does what it says in the title : we can skip empty proposals, but need to increase the loop counter.

Reviewed By: DodgySpaniard

Differential Revision: D29877234

fbshipit-source-id: b377fad331bd036dd85f64bda97dd5feb8d4c7c3

mapillary/OpenSfM,mapillary/OpenSfM,mapillary/OpenSfM,mapillary/OpenSfM,mapillary/OpenSfM