Fix swift-build trouble when using VMs
Fix swift-build trouble when using VMs

Fixes https://bugs.swift.org/browse/SR-166
abertelrud/swift-package-manager,apple/swift-package-manager,sschiau/swift-package-manager,sschiau/swift-package-manager,apple/swift-package-manager,JGiola/swift-package-manager,sschiau/swift-package-manager,JGiola/swift-package-manager,JGiola/swift-package-manager,mxcl/swift-package-manager,vmanot/swift-package-manager,abertelrud/swift-package-manager,mxcl/swift-package-manager,mxcl/swift-package-manager,mxcl/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,JGiola/swift-package-manager,vmanot/swift-package-manager,haskellswift/swift-package-manager,haskellswift/swift-package-manager,sschiau/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,haskellswift/swift-package-manager,JGiola/swift-package-manager,vmanot/swift-package-manager,apple/swift-package-manager,sschiau/swift-package-manager,vmanot/swift-package-manager,abertelrud/swift-package-manager,haskellswift/swift-package-manager,vmanot/swift-package-manager