Only copy bootstrap legacy files when bootstrapping
Only copy bootstrap legacy files when bootstrapping

We should only copy bootstrapping files when we're actually
bootstrapping.

roambotics/swift,roambotics/swift,benlangmuir/swift,ahoppen/swift,roambotics/swift,ahoppen/swift,glessard/swift,apple/swift,roambotics/swift,roambotics/swift,JGiola/swift,JGiola/swift,glessard/swift,apple/swift,ahoppen/swift,glessard/swift,JGiola/swift,benlangmuir/swift,apple/swift,roambotics/swift,glessard/swift,benlangmuir/swift,JGiola/swift,glessard/swift,benlangmuir/swift,apple/swift,glessard/swift,apple/swift,JGiola/swift,benlangmuir/swift,ahoppen/swift,benlangmuir/swift,apple/swift,ahoppen/swift,ahoppen/swift,JGiola/swift