$ git clone -n https://src.fedoraproject.org/rpms/xen.git /var/lib/mock/f33-build-153313-43325/root/chroot_tmpdir/scmroot/xen
Cloning into '/var/lib/mock/f33-build-153313-43325/root/chroot_tmpdir/scmroot/xen'...
$ git reset --hard b64e04acdfdadc67a8d5fcef103af0c63939fc84
HEAD is now at b64e04a fix issues in pygrub dependency found by python 3.8