Bug#962158: lintian: New very problematic --fail-on default value

[Guillem Jover <guillem@debian.org>]

Package: lintian
Version: 2.80.0
Severity: important

[ This probably deserves to be serious, but I'm not sure I can be
  bothered… ]

Hi,

As was mentioned on debian-devel@l.d.o, and on #debian-qa, the new
default is very problematic, and has not been properly justified.

The general expectation is that a linter is supposed to exit non-0
when it finds at least errors. When people use it in manual mode,
they will just see the reported tags, but in automatic settings the
error code is what makes this useful at all.

This change means that any current caller which uses lintian as part
of its acceptance testing will now silently let broken things through
(until someone eventually notices the breakage), some examples of this
in Debian are:

  - dupload/dput/dput-ng
  - sbuild
  - pbuilder
  - check-all-the-things
  - debomatic (?)
  - jenkins-debian-glue
  - pkg-perl-tools
  - dpkg-buildpackage --check-command
  - etc.

Then also any CI setup that uses lintian (say in .gitlab-ci.yml or
.travis, .circleci, or similar stuff).

While these could be adapted in Debian, it would still leave any CI or
in-house setup that calls lintian broken. This is made worse due to the
new option not being available in older releases before the default got
changed, which would imply cumbersome backward compatibility checks that
decide whether to use the new option or not.

If the default change made sense due to some technical rationale, this
effort might be worthwhile, but as it is, this is a bad default that will
require tons of useless work and introduces breakage for no good reason.

Thanks,
Guillem