Comment 3 for bug 1823722

The strings come from mutter and it seems an issue with the template generation in launchpad, from the build log
https://launchpadlibrarian.net/418511049/buildlog_ubuntu-disco-amd64.mutter_3.32.0-1ubuntu2_BUILDING.txt.gz

' dh_translations -O--buildsystem=meson
ninja: Entering directory `/<<PKGBUILDDIR>>/obj-x86_64-linux-gnu'
[0/1] Running external command mutter-pot.
xgettext: warning: file 'data/50-mutter-navigation.xml' extension 'xml' is unknown; will try C
xgettext: warning: file 'data/50-mutter-system.xml' extension 'xml' is unknown; will try C
xgettext: warning: file 'data/50-mutter-wayland.xml' extension 'xml' is unknown; will try C'

The strings from the data/*.xml files are missing from the template (but are listed upstream and in the .po for the source)

Gunnar, is that maybe something you could have a look to? Do you know if the file type can be specified for gettext somewhere? (in the POTFILES.in?)