See the commit 28467cb on the gimp-data-extras repo where I moved this
data in. Not sure why this metadata file was ever pushed to the main
repo as it is obviously for the data-extras package (or else I am
missing some information!).
The old 2017 report where it was originally added:
https://bugzilla.gnome.org/show_bug.cgi?id=763398
As told to us, this is the reference AppStream file testing tool, and it
understands more of the spec.
Also since commit 73e2e701da, appstream-util chokes on newer url types
from the spec. These tags are now supported both in appstream-util and
appstreamcli source code, except that appstreamcli had release 0.15.3,
available in Debian testing, whereas there were apparently no recent
appstream-glib/util release (and none since 2020). So for these various
reasons, let's go with the appstreamcli tool.
The only downside is that appstream package (where appstreamcli lives)
is not available on MSYS2, but since it's only an optional test tool for
XML files which should be common on all platforms, it's probably
acceptable.
Before each release, we prepare now a <release> tag. Unfortunately some
details are not always well known for sure in advance, in particular the
date of release (plans are made to be broken!), and also the release
news URL (since the date is in the URL). So I usually leave them as TODO
and until now, I never forgot to update them just before release. But
there is always the risk of forgetting.
Now the test for the appdata files will also look for remaining "TODO"
in the file if and only if the micro version is even (which means it's a
release). So we won't ever forget to update the file as long as we run
`make check` on the last commit (which we always do obviously).
Jehan