Comment # 6 on bug 1201111 from Benjamin Greiner

> So all projects requiring flufl.i18n fail to build.

I don't understand this. All projects requiring flufl.i18n (python-mailman*)
are python3 only and should depend on python3-flufl.i18n

While switching the package to multi-flavor is a good option so that
python310-flufl.i18n exists and provides python3-flufl.i18n, it does not change
that python3 only packages should depend on the right capability.