fix: mergeInfillLines had a boolean mistake due to 497c969 (CURA-1560)
fix: mergeInfillLines had a boolean mistake due to 497c969 (CURA-1560)

totalretribution/CuraEngine,Ultimaker/CuraEngine,totalretribution/CuraEngine,ROBO3D/CuraEngine,alephobjects/CuraEngine,totalretribution/CuraEngine,alephobjects/CuraEngine,ROBO3D/CuraEngine,Ultimaker/CuraEngine,alephobjects/CuraEngine,ROBO3D/CuraEngine