Bug#985455: python3-pkg-resources: fails to upgrade from 'buster': ValueError: not enough values to unpack (expected 4, got 3) in /usr/bin/py3compile

[Sebastian Ramacher]

Control: reassign -1 python3-joblib 0.17.0-2
Control: tags + patch

On 2021-03-18 14:36:22 +0100, Andreas Beckmann wrote:
> Package: python3-pkg-resources
> Version: 52.0.0-3
> Severity: serious
> User: debian-qa at lists.debian.org
> Usertags: piuparts
> Control: affects -1 + python3-joblib
> 
> Hi,
> 
> during a test with piuparts I noticed your package fails to upgrade from
> 'buster'.
> It installed fine in 'buster', then the upgrade to 'bullseye' fails.
> 
> >From the attached log (scroll to the bottom...):
> 
>   Setting up python3-pkg-resources (52.0.0-3) ...
>   Traceback (most recent call last):
>     File "/usr/bin/py3compile", line 290, in <module>
>       main()
>     File "/usr/bin/py3compile", line 266, in main
>       e_patterns = get_exclude_patterns()
>     File "/usr/bin/py3compile", line 93, in get_exclude_patterns
>       for type_, vers, dname, pattern in get_exclude_patterns_from_dir():
>     File "/usr/share/python3/debpython/__init__.py", line 22, in __call__
>       self.cache[key] = self.func(*args, **kwargs)
>     File "/usr/bin/py3compile", line 68, in get_exclude_patterns_from_dir
>       type_, vrange, dname, pattern = line.split('|', 3)
>   ValueError: not enough values to unpack (expected 4, got 3)
>   dpkg: error processing package python3-pkg-resources (--configure):
>    installed python3-pkg-resources package post-installation script subprocess returned error exit status 1
> 
> I'm not exactly sure which package is to blame here,
> but this looks like some dependencies are not tight enough or
> some Breaks are missing.

The issue is in /usr/share/python3/bcep/python3-joblib. Lines starting
with re are supposed to follow the format

  re|version restriction|path|pattern

joblib's bcep file misses the pattern. py3compile from buster fails to
parse the line, while py3compile from bullseye also handles a missing
pattern. Proposed fix is attached, or otherwise depend on
python3-minimal (>= 3.8.2-2).

Cheers
-- 
Sebastian Ramacher
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