Bug#1090351: /usr/lib/python3/dist-packages/aptsources/distro.py: Calling .lower() method on a 'None' type variable (file: aptsources/distro.py, line 544, function: get_distro)

[Glennie Vignarajah <glennie+debian@glennie.fr>]

Package: python3-apt
Version: 2.9.2
Severity: important
File: /usr/lib/python3/dist-packages/aptsources/distro.py

Dear Maintainer,


   * What led up to the situation?: Setup a node with ansible.

   * What exactly did you do (or not do) that was effective (or
     ineffective)? Run ansible as usual in order to setup a source file
     for apt.

   * What was the outcome of this action? Anisble run fails with

```
    Traceback (most recent call last):
      File "/home/glennie/.ansible/tmp/ansible-tmp-1734426175.6180859-3979780-111839269724897/AnsiballZ_apt_repository.py", line 259, in <module>
        _ansiballz_main()
      File "/home/glennie/.ansible/tmp/ansible-tmp-1734426175.6180859-3979780-111839269724897/AnsiballZ_apt_repository.py", line 249, in _ansiballz_main
        invoke_module(zipped_mod, temp_path, ANSIBALLZ_PARAMS)
      File "/home/glennie/.ansible/tmp/ansible-tmp-1734426175.6180859-3979780-111839269724897/AnsiballZ_apt_repository.py", line 122, in invoke_module
        runpy.run_module(mod_name='ansible.modules.apt_repository', init_globals=dict(_module_fqn='ansible.modules.apt_repository', _modlib_path=modlib_path),
      File "<frozen runpy>", line 226, in run_module
      File "<frozen runpy>", line 98, in _run_module_code
      File "<frozen runpy>", line 88, in _run_code
      File "/tmp/ansible_ansible.builtin.apt_repository_payload_l931syp9/ansible_ansible.builtin.apt_repository_payload.zip/ansible/modules/apt_repository.py", line 195, in <module>
      File "/usr/lib/python3/dist-packages/aptsources/distro.py", line 544, in get_distro
        id = id.lower()
             ^^^^^^^^
    AttributeError: 'NoneType' object has no attribute 'lower'
  msg: |-
    MODULE FAILURE: No start of json char found
    See stdout/stderr for the exact error
```

A simple way to reproduce this is bug is to start a python REPL, then
type:

```
import aptsources.distro as aptsources_distro
distro = aptsources_distro.get_distro()
```

>From what I see, the bug lies at line 544, in `aptsources/distro.py`.
`id` is initalized to `None` in the function signature(line: 529). Then on
line 544, I see `id = id.lower()`. If `id` is not set by the caller, it
fails (as ansible seems do).


May be, the line 544 should be be rewritten to:
```
if id is not None:
  id = id.lower()
```

   * What outcome did you expect instead? Ansible should not fail here


-- System Information:
Debian Release: trixie/sid
  APT prefers unstable
  APT policy: (990, 'unstable'), (500, 'testing'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 6.11.9-amd64 (SMP w/8 CPU threads; PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) (ignored: LC_ALL set to en_US.UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages python3-apt depends on:
ii  distro-info-data   0.63
ii  libapt-pkg6.0t64   2.9.17
ii  libc6              2.40-4
ii  libgcc-s1          14.2.0-8
ii  libstdc++6         14.2.0-8
ii  python-apt-common  2.9.2
ii  python3            3.12.7-1

Versions of packages python3-apt recommends:
ii  iso-codes    4.17.0-1
ii  lsb-release  12.1-1

Versions of packages python3-apt suggests:
ii  apt             2.9.17
pn  python-apt-doc  <none>

-- no debconf information