update-checkout: make cloning idempotent and incremental
update-checkout: make cloning idempotent and incremental

xedin/swift,JaSpa/swift,OscarSwanros/swift,karwa/swift,IngmarStein/swift,practicalswift/swift,jtbandes/swift,kperryua/swift,practicalswift/swift,rudkx/swift,therealbnut/swift,natecook1000/swift,kperryua/swift,benlangmuir/swift,danielmartin/swift,kperryua/swift,ahoppen/swift,aschwaighofer/swift,airspeedswift/swift,shajrawi/swift,gribozavr/swift,tkremenek/swift,modocache/swift,parkera/swift,MukeshKumarS/Swift,dduan/swift,karwa/swift,jmgc/swift,huonw/swift,tinysun212/swift-windows,djwbrown/swift,airspeedswift/swift,devincoughlin/swift,SwiftAndroid/swift,parkera/swift,jckarter/swift,felix91gr/swift,hughbe/swift,swiftix/swift,gmilos/swift,tinysun212/swift-windows,Jnosh/swift,glessard/swift,devincoughlin/swift,Jnosh/swift,austinzheng/swift,alblue/swift,aschwaighofer/swift,adrfer/swift,austinzheng/swift,manavgabhawala/swift,JaSpa/swift,gottesmm/swift,kstaring/swift,xedin/swift,xedin/swift,shajrawi/swift,hooman/swift,swiftix/swift,Jnosh/swift,practicalswift/swift,xedin/swift,felix91gr/swift,Jnosh/swift,therealbnut/swift,jtbandes/swift,tjw/swift,manavgabhawala/swift,manavgabhawala/swift,karwa/swift,natecook1000/swift,gribozavr/swift,austinzheng/swift,ben-ng/swift,ben-ng/swift,gregomni/swift,modocache/swift,roambotics/swift,arvedviehweger/swift,shajrawi/swift,jckarter/swift,jmgc/swift,manavgabhawala/swift,lorentey/swift,CodaFi/swift,sschiau/swift,airspeedswift/swift,ben-ng/swift,kperryua/swift,gribozavr/swift,allevato/swift,jtbandes/swift,ahoppen/swift,kstaring/swift,gottesmm/swift,jopamer/swift,Jnosh/swift,slavapestov/swift,modocache/swift,dduan/swift,zisko/swift,shahmishal/swift,karwa/swift,austinzheng/swift,jopamer/swift,shajrawi/swift,ben-ng/swift,sschiau/swift,jckarter/swift,hooman/swift,danielmartin/swift,harlanhaskins/swift,aschwaighofer/swift,devincoughlin/swift,shajrawi/swift,JaSpa/swift,adrfer/swift,jopamer/swift,lorentey/swift,djwbrown/swift,CodaFi/swift,jckarter/swift,jmgc/swift,therealbnut/swift,apple/swift,alblue/swift,nathawes/swift,IngmarStein/swift,harlanhaskins/swift,shahmishal/swift,slavapestov/swift,harlanhaskins/swift,MukeshKumarS/Swift,hughbe/swift,milseman/swift,frootloops/swift,OscarSwanros/swift,sschiau/swift,therealbnut/swift,rudkx/swift,CodaFi/swift,deyton/swift,gregomni/swift,therealbnut/swift,kstaring/swift,harlanhaskins/swift,aschwaighofer/swift,KrishMunot/swift,nathawes/swift,felix91gr/swift,return/swift,stephentyrone/swift,gregomni/swift,hughbe/swift,hooman/swift,danielmartin/swift,felix91gr/swift,harlanhaskins/swift,dduan/swift,amraboelela/swift,nathawes/swift,tardieu/swift,uasys/swift,calebd/swift,Jnosh/swift,natecook1000/swift,apple/swift,natecook1000/swift,roambotics/swift,kperryua/swift,kperryua/swift,MukeshKumarS/Swift,KrishMunot/swift,JaSpa/swift,return/swift,djwbrown/swift,karwa/swift,lorentey/swift,codestergit/swift,sschiau/swift,parkera/swift,ken0nek/swift,shahmishal/swift,zisko/swift,xedin/swift,johnno1962d/swift,codestergit/swift,hughbe/swift,russbishop/swift,stephentyrone/swift,shajrawi/swift,tjw/swift,uasys/swift,parkera/swift,lorentey/swift,IngmarStein/swift,gmilos/swift,codestergit/swift,aschwaighofer/swift,return/swift,dduan/swift,glessard/swift,gribozavr/swift,JaSpa/swift,MukeshKumarS/Swift,roambotics/swift,danielmartin/swift,johnno1962d/swift,bitjammer/swift,manavgabhawala/swift,xwu/swift,devincoughlin/swift,russbishop/swift,tjw/swift,tkremenek/swift,swiftix/swift,roambotics/swift,arvedviehweger/swift,alblue/swift,huonw/swift,SwiftAndroid/swift,johnno1962d/swift,stephentyrone/swift,ahoppen/swift,zisko/swift,benlangmuir/swift,modocache/swift,bitjammer/swift,brentdax/swift,milseman/swift,slavapestov/swift,gmilos/swift,frootloops/swift,tinysun212/swift-windows,roambotics/swift,huonw/swift,kstaring/swift,gottesmm/swift,xwu/swift,frootloops/swift,gottesmm/swift,sschiau/swift,tkremenek/swift,SwiftAndroid/swift,jopamer/swift,amraboelela/swift,adrfer/swift,glessard/swift,calebd/swift,apple/swift,codestergit/swift,atrick/swift,tkremenek/swift,johnno1962d/swift,codestergit/swift,nathawes/swift,nathawes/swift,tjw/swift,shahmishal/swift,tkremenek/swift,swiftix/swift,xedin/swift,danielmartin/swift,ben-ng/swift,frootloops/swift,frootloops/swift,tjw/swift,apple/swift,stephentyrone/swift,jckarter/swift,jckarter/swift,hooman/swift,tinysun212/swift-windows,johnno1962d/swift,apple/swift,hughbe/swift,deyton/swift,deyton/swift,adrfer/swift,jmgc/swift,uasys/swift,brentdax/swift,ken0nek/swift,felix91gr/swift,return/swift,natecook1000/swift,hooman/swift,huonw/swift,IngmarStein/swift,rudkx/swift,brentdax/swift,bitjammer/swift,gribozavr/swift,jtbandes/swift,atrick/swift,harlanhaskins/swift,felix91gr/swift,IngmarStein/swift,felix91gr/swift,bitjammer/swift,deyton/swift,JGiola/swift,allevato/swift,xwu/swift,karwa/swift,bitjammer/swift,devincoughlin/swift,JGiola/swift,milseman/swift,brentdax/swift,slavapestov/swift,brentdax/swift,sschiau/swift,jmgc/swift,dduan/swift,shahmishal/swift,hooman/swift,jtbandes/swift,lorentey/swift,allevato/swift,roambotics/swift,frootloops/swift,stephentyrone/swift,OscarSwanros/swift,huonw/swift,codestergit/swift,ken0nek/swift,return/swift,MukeshKumarS/Swift,modocache/swift,kstaring/swift,huonw/swift,harlanhaskins/swift,lorentey/swift,practicalswift/swift,alblue/swift,djwbrown/swift,practicalswift/swift,deyton/swift,frootloops/swift,KrishMunot/swift,gottesmm/swift,amraboelela/swift,rudkx/swift,djwbrown/swift,karwa/swift,practicalswift/swift,gribozavr/swift,amraboelela/swift,tkremenek/swift,manavgabhawala/swift,bitjammer/swift,atrick/swift,nathawes/swift,huonw/swift,calebd/swift,jtbandes/swift,CodaFi/swift,sschiau/swift,tinysun212/swift-windows,kstaring/swift,ahoppen/swift,zisko/swift,stephentyrone/swift,austinzheng/swift,devincoughlin/swift,MukeshKumarS/Swift,tinysun212/swift-windows,natecook1000/swift,djwbrown/swift,practicalswift/swift,OscarSwanros/swift,jckarter/swift,OscarSwanros/swift,therealbnut/swift,codestergit/swift,jmgc/swift,aschwaighofer/swift,shajrawi/swift,tardieu/swift,devincoughlin/swift,modocache/swift,alblue/swift,alblue/swift,gottesmm/swift,arvedviehweger/swift,calebd/swift,rudkx/swift,SwiftAndroid/swift,xedin/swift,xwu/swift,parkera/swift,uasys/swift,russbishop/swift,russbishop/swift,kperryua/swift,allevato/swift,adrfer/swift,swiftix/swift,russbishop/swift,amraboelela/swift,tardieu/swift,OscarSwanros/swift,gregomni/swift,tinysun212/swift-windows,zisko/swift,tjw/swift,adrfer/swift,gmilos/swift,JGiola/swift,JGiola/swift,allevato/swift,gmilos/swift,johnno1962d/swift,MukeshKumarS/Swift,arvedviehweger/swift,rudkx/swift,gregomni/swift,ben-ng/swift,russbishop/swift,tardieu/swift,shahmishal/swift,parkera/swift,atrick/swift,austinzheng/swift,return/swift,danielmartin/swift,atrick/swift,austinzheng/swift,jopamer/swift,slavapestov/swift,natecook1000/swift,milseman/swift,dduan/swift,alblue/swift,JaSpa/swift,bitjammer/swift,practicalswift/swift,ahoppen/swift,OscarSwanros/swift,dreamsxin/swift,jopamer/swift,karwa/swift,hooman/swift,calebd/swift,tkremenek/swift,KrishMunot/swift,JGiola/swift,arvedviehweger/swift,brentdax/swift,devincoughlin/swift,benlangmuir/swift,brentdax/swift,danielmartin/swift,ken0nek/swift,shahmishal/swift,CodaFi/swift,jtbandes/swift,dduan/swift,zisko/swift,atrick/swift,gottesmm/swift,swiftix/swift,glessard/swift,allevato/swift,manavgabhawala/swift,arvedviehweger/swift,glessard/swift,shajrawi/swift,hughbe/swift,xwu/swift,calebd/swift,KrishMunot/swift,airspeedswift/swift,KrishMunot/swift,johnno1962d/swift,slavapestov/swift,jmgc/swift,glessard/swift,tjw/swift,ahoppen/swift,gregomni/swift,adrfer/swift,benlangmuir/swift,therealbnut/swift,ken0nek/swift,ben-ng/swift,return/swift,uasys/swift,benlangmuir/swift,SwiftAndroid/swift,parkera/swift,gribozavr/swift,CodaFi/swift,shahmishal/swift,IngmarStein/swift,amraboelela/swift,airspeedswift/swift,arvedviehweger/swift,calebd/swift,dreamsxin/swift,swiftix/swift,sschiau/swift,SwiftAndroid/swift,milseman/swift,allevato/swift,ken0nek/swift,parkera/swift,JGiola/swift,gribozavr/swift,zisko/swift,apple/swift,milseman/swift,lorentey/swift,KrishMunot/swift,gmilos/swift,SwiftAndroid/swift,uasys/swift,airspeedswift/swift,tardieu/swift,lorentey/swift,modocache/swift,kstaring/swift,tardieu/swift,JaSpa/swift,uasys/swift,IngmarStein/swift,benlangmuir/swift,airspeedswift/swift,tardieu/swift,milseman/swift,xwu/swift,aschwaighofer/swift,deyton/swift,djwbrown/swift,ken0nek/swift,jopamer/swift,xedin/swift,Jnosh/swift,deyton/swift,russbishop/swift,xwu/swift,slavapestov/swift,amraboelela/swift,CodaFi/swift,stephentyrone/swift,gmilos/swift,nathawes/swift,hughbe/swift