Bug#996093: lintian: detect variant of Lenna image

[Felix Lechner <felix.lechner@lease-up.com>]

Hi,

On Tue, Oct 12, 2021 at 11:45 PM Andrius Merkys <merkys@debian.org> wrote:
>
> However, license-problem-md5sum-non-free-file seems superfluous to me.
> What do you think?

I agree. Unfortunately, the two checks are in different places. We
have the issue elsewhere in Lintian.

In the future I may separate Lintian's scanning activities from the
hint issuance, which would allow for post-processing. (Another
solution, which I like less, would be to integrate the banned hashes
into Index::Item.) Either way, the hashes are more reliable—plus, the
banned hash table contains other Lenna images [1]—while the name
detection is broader and more user-friendly.

After some contemplation, I left the duplication issue to be solved on
another day.

Kind regards
Felix Lechner

[1] https://salsa.debian.org/lintian/lintian/-/blob/master/data/cruft/non-free-files