As noticed by Dmitry Nedospasov (Cf. [1]), sudoers file should not be copied by default. Move this hook to a role, and add a warning about this in role. [1] http://xen-tools.org/pipermail/xen-tools-dev/2010-July/000146.html
These files are roles which you can use with xen-create-image(1) with the --role= option. If you add new roles to the xen-tools distribution in this directory, please document them in the POD code of bin/xen-create-image under "ROLES".