Bug#1002840: gnome-software: screenshot URLs never update new DEP-11/appstream-data and fail HTTP 404

[Jano John Akim Franke]

Workaround is to download the updated file without 'apt update' to the 
same location and doing an appstream refresh. Screenshots of "Builder" 
are visible after that:

# wget --timestamping 
'https://appstream.debian.org/data/bullseye/main/Components-amd64.yml.gz' -O 
'/var/lib/app-info/yaml/deb.debian.org_debian_dists_bullseye_main_dep11_Components-amd64.yml.gz'
[...]
# ls -l --dereference-command-line 
/var/lib/app-info/yaml/deb.debian.org_debian_dists_bullseye_main_dep11_Components-amd64.yml.gz
-rw-r--r-- 1 root root 6270308 18. Dez 15:25 
/var/lib/app-info/yaml/deb.debian.org_debian_dists_bullseye_main_dep11_Components-amd64.yml.gz
# appstreamcli refresh-cache --force
[...]

The source of these files is configured in 
/etc/apt/apt.conf.d/50appstream of package appstream and can be read for 
example by:
# apt-get indextargets --format '$(URI) $(FILENAME)' 'Component: main' 
'Identifier: DEP-11'
http://deb.debian.org/debian/dists/bullseye/main/dep11/Components-amd64.yml 
/var/lib/apt/lists/deb.debian.org_debian_dists_bullseye_main_dep11_Components-amd64.yml.gz

APT can not be configured to download single files of an otherwise 
non-repo like https://appstream.debian.org/data/bullseye/main/ so the 
files have to be integrated somewhere in the repo for APT to get them or 
have to be synced not using APT.

The changelog tells the download via APT is probably done since 2015, 
but how where updates supposed to work?

<<<
appstream (0.9.0-1) unstable; urgency=medium

   * New upstream release: 0.9.0
   * Adjust to libappstream ABI break
   * Enable APT support

  -- Matthias Klumpp <mak at debian.org>  Sat, 12 Dec 2015 18:44:38 +0100
 >>>