Upgrading system-upgrade-controller fails

Stackspin main recently increased the system-upgrade-controller version from 0.3.1 to 0.4.0. That works for new installs, but fails consistently when upgrading existing clusters:

Helm upgrade failed for release system-upgrade/system-upgrade-controller with chart system-upgrade-controller@0.4.0: cannot patch "system-upgrade" with kind ClusterRoleBinding: ClusterRoleBinding.rbac.authorization.k8s.io "system-upgrade" is invalid: roleRef: Invalid value: rbac.RoleRef{APIGroup:"rbac.authorization.k8s.io", Kind:"ClusterRole", Name:"system-upgrade-controller"}: cannot change roleRef

I've filed a bug report with the chart author, but given that they just copy the manifests from upstream (rancher), I think it's unlikely that they'll have a good fix for this. As a workaround we can instruct flux to uninstall system-upgrade-controller on upgrade failures.