Unexpected warnings for 'appstream validate' on components with merge="append"

[sidt4]

appstreamcli validate support for components with merge="append" was added in #455.

Now, running validation on org.gnome.App-list.xml.txt obtained from https://gitlab.gnome.org/GNOME/gnome-app-list/ results in the following warnings.

$ appstreamcli validate _build/org.gnome.App-list.xml

I: app.drey.Biblioteca:9: nonstandard-gnome-extension kudos
W: app.drey.Biblioteca:~: url-homepage-missing
W: app.drey.Biblioteca:~: category-invalid Featured
W: app.drey.Biblioteca:~: all-categories-ignored
I: app.drey.Biblioteca:~: developer-info-missing

I: app.drey.Dialect:21: nonstandard-gnome-extension kudos
W: app.drey.Dialect:~: url-homepage-missing
W: app.drey.Dialect:~: category-invalid Featured
W: app.drey.Dialect:~: all-categories-ignored
I: app.drey.Dialect:~: developer-info-missing
...
...
✘ Validation failed: warnings: 360, infos: 194
$ echo $?
3

I guess except for nonstandard-gnome-extension kudos, validation should not report any warnings.

$ appstreamcli --version
AppStream version: 1.0.3

[sidt4]

Refer pipeline https://gitlab.gnome.org/sid/gnome-app-list/-/jobs/4159767.