Regression since ~1.2.10 in .jar timestamp handling?

Just quickly braindumping for now but it looks like we are not normalising timestamps correctly in .jar files:

│ ├── data.tar.xz
│ │ ├── data.tar
│ │ │ ├── ./usr/share/java/eclipse-core-filesystem-1.7.400.jar
│ │ │ │ ├── zipinfo /dev/stdin
│ │ │ │ │ @@ -1,51 +1,51 @@
│ │ │ │ │  Zip file size: 57912 bytes, number of entries: 49
│ │ │ │ │ --rw-r--r--  2.0 unx      978 b- defN 19-Jul-19 17:09 META-INF/MANIFEST.MF
│ │ │ │ │ +-rw-r--r--  2.0 unx      978 b- defN 20-Aug-22 01:35 META-INF/MANIFEST.MF

This was built with 1.2.3-1 according to its `.buildinfo. Relevant changelog entries are:

strip-nondeterminism (1.2.3-1) unstable; urgency=medium

  * Don't just run the tests but build the Debian package instead using Salsa's
    centralised scripts so that we get code coverage, Lintian, autopkgtests,
    etc.
  * Drop misleading MANIFEST and MANIFEST.SKIP files as they are not used by
    our release processes.
  * Update debian/gbp.conf after merge of 'debian' branch.

 -- Chris Lamb <lamby@debian.org>  Thu, 18 Jul 2019 10:05:14 -0300

strip-nondeterminism (1.2.2-1) unstable; urgency=medium

  * Actually replace all instances of libmonkey-patch-perl with
    libsub-override-perl (re. #931730)
  * Update gitlab-ci.yml:
    - No need to specify not building the "debian" branch; it has no
      build configuration file.
    - Don't build (release) tags.

 -- Chris Lamb <lamby@debian.org>  Mon, 15 Jul 2019 10:41:41 -0300

strip-nondeterminism (1.2.1-1) unstable; urgency=medium

  [ Niko Tyni ]
  * Use Sub::Override for Archive::Zip workarounds instead of Monkey::Patch
    (see reproducible-builds/strip-nondeterminism#8 for more information).
    (Closes: #931730)

  [ Chris Lamb ]
  * Add a ".gitlab-ci.yml" to automatically run the testsuite on
    salsa.debian.org.

 -- Chris Lamb <lamby@debian.org>  Mon, 15 Jul 2019 10:31:13 -0300

See issue #8. Pinging @ntyni but merely for early visibility, not necessary a request for comment/action at this point :)