Diff of the two buildlogs:

--
--- b1/build.log	2025-01-10 11:01:10.633925465 +0000
+++ b2/build.log	2025-01-10 11:06:48.022564720 +0000
@@ -1,6 +1,6 @@
 I: pbuilder: network access will be disabled during build
-I: Current time: Thu Jan  9 22:58:37 -12 2025
-I: pbuilder-time-stamp: 1736506717
+I: Current time: Sat Jan 11 01:01:21 +14 2025
+I: pbuilder-time-stamp: 1736506881
 I: Building the build Environment
 I: extracting base tarball [/var/cache/pbuilder/unstable-reproducible-base.tgz]
 I: copying local configuration
@@ -22,52 +22,84 @@
 dpkg-source: info: unpacking ocaml-ffmpeg_1.2.1-1.debian.tar.xz
 I: Not using root during the build.
 I: Installing the build-deps
-I: user script /srv/workspace/pbuilder/24801/tmp/hooks/D02_print_environment starting
+I: user script /srv/workspace/pbuilder/32274/tmp/hooks/D01_modify_environment starting
+debug: Running on virt64a.
+I: Changing host+domainname to test build reproducibility
+I: Adding a custom variable just for the fun of it...
+I: Changing /bin/sh to bash
+'/bin/sh' -> '/bin/bash'
+lrwxrwxrwx 1 root root 9 Jan 10 11:01 /bin/sh -> /bin/bash
+I: Setting pbuilder2's login shell to /bin/bash
+I: Setting pbuilder2's GECOS to second user,second room,second work-phone,second home-phone,second other
+I: user script /srv/workspace/pbuilder/32274/tmp/hooks/D01_modify_environment finished
+I: user script /srv/workspace/pbuilder/32274/tmp/hooks/D02_print_environment starting
 I: set
-  BUILDDIR='/build/reproducible-path'
-  BUILDUSERGECOS='first user,first room,first work-phone,first home-phone,first other'
-  BUILDUSERNAME='pbuilder1'
-  BUILD_ARCH='armhf'
-  DEBIAN_FRONTEND='noninteractive'
-  DEB_BUILD_OPTIONS='buildinfo=+all reproducible=+all parallel=3 '
-  DISTRIBUTION='unstable'
-  HOME='/root'
-  HOST_ARCH='armhf'
+  BASH=/bin/sh
+  BASHOPTS=checkwinsize:cmdhist:complete_fullquote:extquote:force_fignore:globasciiranges:globskipdots:hostcomplete:interactive_comments:patsub_replacement:progcomp:promptvars:sourcepath
+  BASH_ALIASES=()
+  BASH_ARGC=()
+  BASH_ARGV=()
+  BASH_CMDS=()
+  BASH_LINENO=([0]="12" [1]="0")
+  BASH_LOADABLES_PATH=/usr/local/lib/bash:/usr/lib/bash:/opt/local/lib/bash:/usr/pkg/lib/bash:/opt/pkg/lib/bash:.
+  BASH_SOURCE=([0]="/tmp/hooks/D02_print_environment" [1]="/tmp/hooks/D02_print_environment")
+  BASH_VERSINFO=([0]="5" [1]="2" [2]="37" [3]="1" [4]="release" [5]="arm-unknown-linux-gnueabihf")
+  BASH_VERSION='5.2.37(1)-release'
+  BUILDDIR=/build/reproducible-path
+  BUILDUSERGECOS='second user,second room,second work-phone,second home-phone,second other'
+  BUILDUSERNAME=pbuilder2
+  BUILD_ARCH=armhf
+  DEBIAN_FRONTEND=noninteractive
+  DEB_BUILD_OPTIONS='buildinfo=+all reproducible=+all parallel=4 '
+  DIRSTACK=()
+  DISTRIBUTION=unstable
+  EUID=0
+  FUNCNAME=([0]="Echo" [1]="main")
+  GROUPS=()
+  HOME=/root
+  HOSTNAME=i-capture-the-hostname
+  HOSTTYPE=arm
+  HOST_ARCH=armhf
   IFS=' 	
   '
-  INVOCATION_ID='ed68f4ca779c4024a68f80a5eade1fee'
-  LANG='C'
-  LANGUAGE='en_US:en'
-  LC_ALL='C'
-  MAIL='/var/mail/root'
-  OPTIND='1'
-  PATH='/usr/sbin:/usr/bin:/sbin:/bin:/usr/games'
-  PBCURRENTCOMMANDLINEOPERATION='build'
-  PBUILDER_OPERATION='build'
-  PBUILDER_PKGDATADIR='/usr/share/pbuilder'
-  PBUILDER_PKGLIBDIR='/usr/lib/pbuilder'
-  PBUILDER_SYSCONFDIR='/etc'
-  PPID='24801'
-  PS1='# '
-  PS2='> '
+  INVOCATION_ID=27665edda71e450a8da4cfd23efc3cb4
+  LANG=C
+  LANGUAGE=it_CH:it
+  LC_ALL=C
+  MACHTYPE=arm-unknown-linux-gnueabihf
+  MAIL=/var/mail/root
+  OPTERR=1
+  OPTIND=1
+  OSTYPE=linux-gnueabihf
+  PATH=/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/i/capture/the/path
+  PBCURRENTCOMMANDLINEOPERATION=build
+  PBUILDER_OPERATION=build
+  PBUILDER_PKGDATADIR=/usr/share/pbuilder
+  PBUILDER_PKGLIBDIR=/usr/lib/pbuilder
+  PBUILDER_SYSCONFDIR=/etc
+  PIPESTATUS=([0]="0")
+  POSIXLY_CORRECT=y
+  PPID=32274
   PS4='+ '
-  PWD='/'
-  SHELL='/bin/bash'
-  SHLVL='2'
-  SUDO_COMMAND='/usr/bin/timeout -k 18.1h 18h /usr/bin/ionice -c 3 /usr/bin/nice /usr/sbin/pbuilder --build --configfile /srv/reproducible-results/rbuild-debian/r-b-build.dzLQppo0/pbuilderrc_4uKT --distribution unstable --hookdir /etc/pbuilder/first-build-hooks --debbuildopts -b --basetgz /var/cache/pbuilder/unstable-reproducible-base.tgz --buildresult /srv/reproducible-results/rbuild-debian/r-b-build.dzLQppo0/b1 --logfile b1/build.log ocaml-ffmpeg_1.2.1-1.dsc'
-  SUDO_GID='110'
-  SUDO_UID='103'
-  SUDO_USER='jenkins'
-  TERM='unknown'
-  TZ='/usr/share/zoneinfo/Etc/GMT+12'
-  USER='root'
-  _='/usr/bin/systemd-run'
-  http_proxy='http://10.0.0.15:3142/'
+  PWD=/
+  SHELL=/bin/bash
+  SHELLOPTS=braceexpand:errexit:hashall:interactive-comments:posix
+  SHLVL=3
+  SUDO_COMMAND='/usr/bin/timeout -k 24.1h 24h /usr/bin/ionice -c 3 /usr/bin/nice -n 11 /usr/bin/unshare --uts -- /usr/sbin/pbuilder --build --configfile /srv/reproducible-results/rbuild-debian/r-b-build.dzLQppo0/pbuilderrc_l2sX --distribution unstable --hookdir /etc/pbuilder/rebuild-hooks --debbuildopts -b --basetgz /var/cache/pbuilder/unstable-reproducible-base.tgz --buildresult /srv/reproducible-results/rbuild-debian/r-b-build.dzLQppo0/b2 --logfile b2/build.log ocaml-ffmpeg_1.2.1-1.dsc'
+  SUDO_GID=114
+  SUDO_UID=108
+  SUDO_USER=jenkins
+  TERM=unknown
+  TZ=/usr/share/zoneinfo/Etc/GMT-14
+  UID=0
+  USER=root
+  _='I: set'
+  http_proxy=http://10.0.0.15:3142/
 I: uname -a
-  Linux virt32z 6.1.0-28-armmp-lpae #1 SMP Debian 6.1.119-1 (2024-11-22) armv7l GNU/Linux
+  Linux i-capture-the-hostname 6.1.0-28-arm64 #1 SMP Debian 6.1.119-1 (2024-11-22) aarch64 GNU/Linux
 I: ls -l /bin
   lrwxrwxrwx 1 root root 7 Nov 22 14:40 /bin -> usr/bin
-I: user script /srv/workspace/pbuilder/24801/tmp/hooks/D02_print_environment finished
+I: user script /srv/workspace/pbuilder/32274/tmp/hooks/D02_print_environment finished
  -> Attempting to satisfy build-dependencies
  -> Creating pbuilder-satisfydepends-dummy package
 Package: pbuilder-satisfydepends-dummy
@@ -381,7 +413,7 @@
 Get: 254 http://deb.debian.org/debian unstable/main armhf ocaml-findlib armhf 1.9.6-3 [263 kB]
 Get: 255 http://deb.debian.org/debian unstable/main armhf pkgconf-bin armhf 1.8.1-4 [29.2 kB]
 Get: 256 http://deb.debian.org/debian unstable/main armhf pkgconf armhf 1.8.1-4 [26.1 kB]
-Fetched 203 MB in 22s (9329 kB/s)
+Fetched 203 MB in 4s (53.9 MB/s)
 Preconfiguring packages ...
 Selecting previously unselected package sensible-utils.
 (Reading database ... 
(Reading database ... 5%
(Reading database ... 10%
(Reading database ... 15%
(Reading database ... 20%
(Reading database ... 25%
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(Reading database ... 45%
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(Reading database ... 60%
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(Reading database ... 80%
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(Reading database ... 90%
(Reading database ... 95%
(Reading database ... 100%
(Reading database ... 19562 files and directories currently installed.)
@@ -1426,7 +1458,11 @@
 Building tag database...
  -> Finished parsing the build-deps
 I: Building the package
-I: Running cd /build/reproducible-path/ocaml-ffmpeg-1.2.1/ && env PATH="/usr/sbin:/usr/bin:/sbin:/bin:/usr/games" HOME="/nonexistent/first-build" dpkg-buildpackage -us -uc -b && env PATH="/usr/sbin:/usr/bin:/sbin:/bin:/usr/games" HOME="/nonexistent/first-build" dpkg-genchanges -S  > ../ocaml-ffmpeg_1.2.1-1_source.changes
+I: user script /srv/workspace/pbuilder/32274/tmp/hooks/A99_set_merged_usr starting
+Not re-configuring usrmerge for unstable
+I: user script /srv/workspace/pbuilder/32274/tmp/hooks/A99_set_merged_usr finished
+hostname: Name or service not known
+I: Running cd /build/reproducible-path/ocaml-ffmpeg-1.2.1/ && env PATH="/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/i/capture/the/path" HOME="/nonexistent/second-build" dpkg-buildpackage -us -uc -b && env PATH="/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/i/capture/the/path" HOME="/nonexistent/second-build" dpkg-genchanges -S  > ../ocaml-ffmpeg_1.2.1-1_source.changes
 dpkg-buildpackage: info: source package ocaml-ffmpeg
 dpkg-buildpackage: info: source version 1.2.1-1
 dpkg-buildpackage: info: source distribution unstable
@@ -1447,7 +1483,7 @@
    dh_ocamlinit -O--buildsystem=ocaml_dune
    dh_auto_configure -O--buildsystem=ocaml_dune
    dh_auto_build -O--buildsystem=ocaml_dune
-	dune build -j 3 -p ffmpeg-avcodec,ffmpeg-avdevice,ffmpeg-avfilter,ffmpeg-av,ffmpeg-avutil,ffmpeg-swresample,ffmpeg-swscale,ffmpeg
+	dune build -j 4 -p ffmpeg-avcodec,ffmpeg-avdevice,ffmpeg-avfilter,ffmpeg-av,ffmpeg-avutil,ffmpeg-swresample,ffmpeg-swscale,ffmpeg
 (cd _build/default/avcodec && /usr/bin/arm-linux-gnueabihf-gcc -O2 -fno-strict-aliasing -fwrapv -pthread -fPIC -g -O2 -Werror=implicit-function-declaration -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -pthread -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64 -Wdate-time -D_FORTIFY_SOURCE=2 -I/usr/include/arm-linux-gnueabihf -g -I /usr/lib/arm-linux-gnueabihf/ocaml/5.2.0 -I /usr/lib/arm-linux-gnueabihf/ocaml/5.2.0/threads -I /usr/lib/arm-linux-gnueabihf/ocaml/5.2.0/unix -I ../avutil -o avcodec_stubs.o -c avcodec_stubs.c)
 avcodec_stubs.c: In function 'ocaml_avcodec_get_supported_channel_layouts':
 avcodec_stubs.c:1294:3: warning: 'ch_layouts' is deprecated [-Wdeprecated-declarations]
@@ -1548,7 +1584,7 @@
   215 |     const enum AVPixelFormat *pix_fmts;     ///< @deprecated use avcodec_get_supported_config()
       |                               ^~~~~~~~
    dh_auto_test -O--buildsystem=ocaml_dune
-	dune runtest -j 3 -p ffmpeg-avcodec,ffmpeg-avdevice,ffmpeg-avfilter,ffmpeg-av,ffmpeg-avutil,ffmpeg-swresample,ffmpeg-swscale,ffmpeg
+	dune runtest -j 4 -p ffmpeg-avcodec,ffmpeg-avdevice,ffmpeg-avfilter,ffmpeg-av,ffmpeg-avutil,ffmpeg-swresample,ffmpeg-swscale,ffmpeg
    create-stamp debian/debhelper-build-stamp
    dh_testroot -O--buildsystem=ocaml_dune
    dh_prep -O--buildsystem=ocaml_dune
@@ -1581,9 +1617,9 @@
 dpkg-gencontrol: warning: Depends field of package libffmpeg-ocaml-dev: substitution variable ${shlibs:Depends} used, but is not defined
    dh_md5sums -O--buildsystem=ocaml_dune
    dh_builddeb -O--buildsystem=ocaml_dune
+dpkg-deb: building package 'libffmpeg-ocaml-dev' in '../libffmpeg-ocaml-dev_1.2.1-1_armhf.deb'.
 dpkg-deb: building package 'libffmpeg-ocaml' in '../libffmpeg-ocaml_1.2.1-1_armhf.deb'.
 dpkg-deb: building package 'libffmpeg-ocaml-dbgsym' in '../libffmpeg-ocaml-dbgsym_1.2.1-1_armhf.deb'.
-dpkg-deb: building package 'libffmpeg-ocaml-dev' in '../libffmpeg-ocaml-dev_1.2.1-1_armhf.deb'.
  dpkg-genbuildinfo --build=binary -O../ocaml-ffmpeg_1.2.1-1_armhf.buildinfo
  dpkg-genchanges --build=binary -O../ocaml-ffmpeg_1.2.1-1_armhf.changes
 dpkg-genchanges: info: binary-only upload (no source code included)
@@ -1591,12 +1627,14 @@
 dpkg-buildpackage: info: binary-only upload (no source included)
 dpkg-genchanges: info: including full source code in upload
 I: copying local configuration
+I: user script /srv/workspace/pbuilder/32274/tmp/hooks/B01_cleanup starting
+I: user script /srv/workspace/pbuilder/32274/tmp/hooks/B01_cleanup finished
 I: unmounting dev/ptmx filesystem
 I: unmounting dev/pts filesystem
 I: unmounting dev/shm filesystem
 I: unmounting proc filesystem
 I: unmounting sys filesystem
 I: cleaning the build env 
-I: removing directory /srv/workspace/pbuilder/24801 and its subdirectories
-I: Current time: Thu Jan  9 23:01:06 -12 2025
-I: pbuilder-time-stamp: 1736506866
+I: removing directory /srv/workspace/pbuilder/32274 and its subdirectories
+I: Current time: Sat Jan 11 01:06:43 +14 2025
+I: pbuilder-time-stamp: 1736507203