The build timestamp is getting embedded in various shipped .pot files:

https://reproduce.debian.net/all/api/v1/builds/234931/artifacts/514050/diffoscope

  │ │ ├── ./usr/lib/python3/dist-packages/horizon/locale/django.pot
  ...
  │ │ │ -"POT-Creation-Date: 2026-09-21 07:22+0000\n"
  │ │ │ +"POT-Creation-Date: 2026-09-26 10:01+0000\n"

This issue is currently blocking migration to testing:

https://reproduce.debian.net/excuses.html?source_name=horizon

This appears to have been introduced in upstream version 26.0.0 and is
present in newer versions as well:

https://tests.reproducible-builds.org/debian/history/amd64/horizon.html

Reverting an upstream commit appears to resolve the issue:

  63ed6a1d6b1fe3f153b80ed580c7a49eaf2f1d12
  Avoid calling setup.py in the extract_messages command

Although it is hopefully possible to fix this in some better way than
reverting the upstream commit, offering the attached patch as a
workaround until a better solution that can be merged upstream can be
found.


live well,
  vagrant

Hello,

Bug #1149638 in horizon reported by you has been fixed in the
Git repository and is awaiting an upload. You can see the commit
message below and you can check the diff of the fix at:

https://salsa.debian.org/openstack-team/services/horizon/-/commit/097a5c9b8f35745a5c187ce51faa421c0310e7ba
------------------------------------------------------------------------
Strip POT-Creation-Date from shipped .pot files

babel always embeds the current build time as POT-Creation-Date
when regenerating the .pot files at build time, making builds
unreproducible. Strip that header from the generated files in
debian/compile-messages (Closes: #1149638). Thanks Vagrant
Cascadian for the bug report.
------------------------------------------------------------------------

(this message was generated automatically)
-- 
Greetings

https://bugs.debian.org/1149638

We believe that the bug you reported is fixed in the latest version of
horizon, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1149638@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Thomas Goirand <zigo@debian.org> (supplier of updated horizon package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Tue, 06 Oct 2026 16:47:01 +0200
Source: horizon
Architecture: source
Version: 3:27.0.0-2
Distribution: unstable
Urgency: medium
Maintainer: Debian OpenStack <team+openstack@tracker.debian.org>
Changed-By: Thomas Goirand <zigo@debian.org>
Closes: 1149638
Changes:
 horizon (3:27.0.0-2) unstable; urgency=medium
 .
   * Fixed a reproducible-builds issue in python3-horizon: babel always
     embeds the current build time as POT-Creation-Date when regenerating
     the .pot files at build time, making builds unreproducible. Strip
     that header from the generated files in debian/compile-messages
     (Closes: #1149638). Thanks Vagrant Cascadian for the bug report.
Checksums-Sha1:
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 874c724cb2a31154a7a0be5b26e2146b0bdcf668 36300 horizon_27.0.0-2.debian.tar.xz
 84f344005a569fd972ddccdf8daaac41b153ca36 17464 horizon_27.0.0-2_amd64.buildinfo
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 ff06ab625190511b9e42d3af37c9c445fc3ed7228c76a5f43db500601bd04d8f 36300 horizon_27.0.0-2.debian.tar.xz
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