The systemd busctl tool chokes on introspection XML

[nojocodex]

The systemd busctl on Ubuntu 20.04 doesn't like the xmlns:doc attribute that dbus-objects adds to the <node> element of the introspection XML. Just leaving out the attribute makes busctl happy.

Reproduction:

$ busctl introspect <interface> <path>
Unexpected <node> attribute xmlns:doc.

Dunno if you want to fix this, as I think the problem is really in busctl (at least, there are official-ish examples which indicate including xmlns:doc is perfectly valid: https://dbus.freedesktop.org/doc/dbus-api-design.html). Also, I don't know whether anyone besides me actually uses busctl, so it may not be worth doing anything about.

OTOH, the xmlns:doc attribute seems optional (at least, there are official-ish examples without it: https://dbus.freedesktop.org/doc/dbus-specification.html#introspection-format), so a fix is easy and AFAICT harmless.

[FFY00]

If this is causing issues it can be temporarily removed, but I'd like to see it fixed in busctl. Could you open an issue there? Please ping me if you do.

[FFY00]

Mitigated in #21, but I will keep this open to track the busctl progress.