$ git clone -n https://github.com/xcp-ng-rpms/xenserver-firstboot.git /var/lib/mock/v7.99-base-735-317/root/chroot_tmpdir/scmroot/xenserver-firstboot
Cloning into '/var/lib/mock/v7.99-base-735-317/root/chroot_tmpdir/scmroot/xenserver-firstboot'...
$ git reset --hard b8a67e05aab347542d18d01feeb57d5afbfba815
fatal: Could not parse object 'b8a67e05aab347542d18d01feeb57d5afbfba815'.