apt.Cache.clear() -> apt.Cache._depcache.init() raises Error

[errors.ubuntu.com bug bridge]

Unattended-upgrades 2.1 triggers the following crash in python-apt:

  File "/usr/bin/unattended-upgrade", line 1706, in try_to_upgrade
    cache.mark_upgrade_adjusted(pkg, from_user=not pkg.is_auto_installed)
  File "/usr/bin/unattended-upgrade", line 438, in mark_upgrade_adjusted
    self.call_adjusted(apt.package.Package.mark_upgrade, pkg, **kwargs)
  File "/usr/bin/unattended-upgrade", line 397, in call_adjusted
    self.clear()
  File "/usr/lib/python3/dist-packages/apt/cache.py", line 700, in clear
    self._depcache.init()
apt_pkg.Error: E:The package intellij-idea-ultimate needs to be reinstalled, but I can't find an archive for it.

I think .clear() should not raise an error, but if it should u-u can catch that.

---

The Ubuntu Error Tracker has been receiving reports about a problem regarding unattended-upgrades. This problem was most recently seen with package version 2.1, the problem page at https://errors.ubuntu.com/problem/798f1ab5a4a2784a0fadd6034a875901345682f9 contains more details, including versions of packages affected, stacktrace or traceback, and individual crash reports.
If you do not have access to the Ubuntu Error Tracker and are a software developer, you can request it at http://forms.canonical.com/reports/.

[Julian Andres Klode (juliank)]

If clear() fails, you're a bit lost, but I'm not sure what you'd want to do here, the system is completely broken at that point.

[Balint Reczey (rbalint)]

@juliank Well, I have to agree in this particular case. If the package archive was available u-u could try to fix it by even calling dpkg to reinstall it, but the archive was not available.

At least u-u logs this error and includes it in the email now and only after that it raises it again for apport to get it reported.

The error has also been reported with piper broken, maybe there was an issue running the maintainer scripts which calls py3compile:

#!/bin/sh
set -e

# Automatically added by dh_python3:
if which py3compile >/dev/null 2>&1; then
        py3compile -p piper
fi
if which pypy3compile >/dev/null 2>&1; then
        pypy3compile -p piper || true
fi

# End automatically added section

[Balint Reczey (rbalint)]

Unattended-upgrades may handle this exception by exiting with failure and not re-raising it to the top.