$ git clone -n https://src.fedoraproject.org/rpms/swift-lang.git /var/lib/mock/f31-build-115400-34500/root/chroot_tmpdir/scmroot/swift-lang
Cloning into '/var/lib/mock/f31-build-115400-34500/root/chroot_tmpdir/scmroot/swift-lang'...
$ git reset --hard d750885f12490d8bec235de22faae85767ebc08f
HEAD is now at d750885 First public build of Swift 5.1