Bug#855111: apt: Missing dep11 info on mirror breaks update when appstream is installed

["Christopher Huhn, GSI" <C.Huhn@gsi.de>]

Package: apt
Version: 1.4~rc1
Severity: important

Hi,

for testing purposes I installed plasma-discover on my Stretch box.
That pulled appstream, enabling fetching of DEP-11 stuff,
which our debmirror/stable powered local mirror does not host.

The inability to fetch DEP-11 icons makes apt fail with what looks
like a minor error, but in fact it will not update the package lists.
Therefore apt-get upgrade, unattended-upgrades aso. will report that the system is up to date without installing any updates.

After purging appstream now my system has to upgrade some hundred packages :(

IMHO apt must not abort on missing DEP-11 information as
I'd consider that purely optional information.

In fact this is #824563 but I did not manage to unarchive and reopen that bug.

Kind regards,
    Christopher

-- Package-specific info:

-- (/etc/apt/preferences present, but not submitted) --


-- (/etc/apt/preferences.d/gsi present, but not submitted) --


-- (/etc/apt/sources.list present, but not submitted) --


-- (/etc/apt/sources.list.d/gsi-repository.list present, but not submitted) --


-- (/etc/apt/sources.list.d/stretch-updates.list present, but not submitted) --


-- System Information:
Debian Release: 9.0
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.9.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=de_DE.ISO-8859-1, LC_CTYPE=de_DE.ISO-8859-1 (charmap=ISO-8859-1)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages apt depends on:
ii  adduser                 3.115
ii  debian-archive-keyring  2014.3
ii  gpgv                    2.1.18-3
ii  init-system-helpers     1.47
ii  libapt-pkg5.0           1.4~rc1
ii  libc6                   2.24-9
ii  libgcc1                 1:6.3.0-6
ii  libstdc++6              6.3.0-6

Versions of packages apt recommends:
ii  gnupg   2.1.18-3
ii  gnupg2  2.1.18-3

Versions of packages apt suggests:
pn  apt-doc         <none>
ii  aptitude        0.8.5-1
ii  dpkg-dev        1.18.22
pn  powermgmt-base  <none>
ii  python-apt      1.4.0~beta2
ii  synaptic        0.84.1

-- no debconf information