bug#23776: Perl's .pod files include timestamps, making Perl package builds non-deterministic

[Leo Famulari]

On Thu, Jun 16, 2016 at 11:39:27AM -0400, Leo Famulari wrote:
> On Thu, Jun 16, 2016 at 01:33:46PM +0200, Ludovic Courtès wrote:
> > The problem is described in 
> > <git://git.debian.org/git/reproducible/notes.git>:
> > 
> > --8<---------------cut here---------------start------------->8---
> > timestamps_in_documentation_generated_by_podman:
> >   description: |
> >     The module Pod::Man includes timestamps in its embedded manpages:
> >     
> > http://sources.debian.net/src/perl/latest/cpan/podlators/lib/Pod/Man.pm/?hl=1700#L977
> >     They should be based on the mtime of the original file.
> >   url: 
> > https://wiki.debian.org/ReproducibleBuilds/TimestampsInManpagesGeneratedByPodMan
> 
> According to the information on this page, we should set POD_MAN_DATE
> while building. Should we make the perl-build-system export this
> variable? Set to SOURCE_DATE_EPOCH?

I noticed that Pod::Man is supposed to respect SOURCE_DATE_EPOCH, as of
the upstream module version 4.03 (released 2015-12-06). Does anyone know
how to check the version of the module bundled into perl?

[0]
https://metacpan.org/pod/Pod::Man#date

[1]
https://www.eyrie.org/~eagle/software/podlators/news.html