update-checkout: change --clone to also update repositories
update-checkout: change --clone to also update repositories

--clone used to skip updating the repositories, which was causing
confusion.  Developers expect update-checkout to update their local
copy, and optionally clone extra repositories.

khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift