Diff of the two buildlogs:

--
--- b1/build.log	2024-10-11 14:27:18.276789865 +0000
+++ b2/build.log	2024-10-11 14:28:17.742258580 +0000
@@ -1,6 +1,6 @@
 I: pbuilder: network access will be disabled during build
-I: Current time: Fri Oct 11 02:25:54 -12 2024
-I: pbuilder-time-stamp: 1728656754
+I: Current time: Sat Oct 12 04:27:27 +14 2024
+I: pbuilder-time-stamp: 1728656847
 I: Building the build Environment
 I: extracting base tarball [/var/cache/pbuilder/unstable-reproducible-base.tgz]
 I: copying local configuration
@@ -26,52 +26,84 @@
 dpkg-source: info: unpacking variantslib_0.17.0-1.debian.tar.xz
 I: Not using root during the build.
 I: Installing the build-deps
-I: user script /srv/workspace/pbuilder/22024/tmp/hooks/D02_print_environment starting
+I: user script /srv/workspace/pbuilder/31087/tmp/hooks/D01_modify_environment starting
+debug: Running on virt64z.
+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 Oct 11 14:27 /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/31087/tmp/hooks/D01_modify_environment finished
+I: user script /srv/workspace/pbuilder/31087/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]="32" [3]="1" [4]="release" [5]="arm-unknown-linux-gnueabihf")
+  BASH_VERSION='5.2.32(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='8a52f1fe0ae645f9aa5aa0d38a93aaeb'
-  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='22024'
-  PS1='# '
-  PS2='> '
+  INVOCATION_ID=bd053fea2a464d52bbc35a8a82af88c5
+  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=31087
   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.rnyfaswb/pbuilderrc_QeCP --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.rnyfaswb/b1 --logfile b1/build.log variantslib_0.17.0-1.dsc'
-  SUDO_GID='112'
-  SUDO_UID='106'
-  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.rnyfaswb/pbuilderrc_UInu --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.rnyfaswb/b2 --logfile b2/build.log variantslib_0.17.0-1.dsc'
+  SUDO_GID=110
+  SUDO_UID=103
+  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 virt32b 6.1.0-26-armmp-lpae #1 SMP Debian 6.1.112-1 (2024-09-30) armv7l GNU/Linux
+  Linux i-capture-the-hostname 6.1.0-26-arm64 #1 SMP Debian 6.1.112-1 (2024-09-30) aarch64 GNU/Linux
 I: ls -l /bin
   lrwxrwxrwx 1 root root 7 Aug  4 21:30 /bin -> usr/bin
-I: user script /srv/workspace/pbuilder/22024/tmp/hooks/D02_print_environment finished
+I: user script /srv/workspace/pbuilder/31087/tmp/hooks/D02_print_environment finished
  -> Attempting to satisfy build-dependencies
  -> Creating pbuilder-satisfydepends-dummy package
 Package: pbuilder-satisfydepends-dummy
@@ -166,7 +198,7 @@
 Get: 47 http://deb.debian.org/debian unstable/main armhf libfindlib-ocaml armhf 1.9.6-3 [128 kB]
 Get: 48 http://deb.debian.org/debian unstable/main armhf ocaml-dune armhf 3.16.0-2+b1 [970 kB]
 Get: 49 http://deb.debian.org/debian unstable/main armhf ocaml-findlib armhf 1.9.6-3 [263 kB]
-Fetched 85.0 MB in 2s (47.6 MB/s)
+Fetched 85.0 MB in 3s (31.4 MB/s)
 debconf: delaying package configuration, since apt-utils is not installed
 Selecting previously unselected package sensible-utils.
 (Reading database ... 
(Reading database ... 5%
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(Reading database ... 90%
(Reading database ... 95%
(Reading database ... 100%
(Reading database ... 19519 files and directories currently installed.)
@@ -377,7 +409,11 @@
 Building tag database...
  -> Finished parsing the build-deps
 I: Building the package
-I: Running cd /build/reproducible-path/variantslib-0.17.0/ && 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  > ../variantslib_0.17.0-1_source.changes
+I: user script /srv/workspace/pbuilder/31087/tmp/hooks/A99_set_merged_usr starting
+Not re-configuring usrmerge for unstable
+I: user script /srv/workspace/pbuilder/31087/tmp/hooks/A99_set_merged_usr finished
+hostname: Name or service not known
+I: Running cd /build/reproducible-path/variantslib-0.17.0/ && 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  > ../variantslib_0.17.0-1_source.changes
 dpkg-buildpackage: info: source package variantslib
 dpkg-buildpackage: info: source version 1:0.17.0-1
 dpkg-buildpackage: info: source distribution unstable
@@ -398,9 +434,9 @@
    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 variantslib
+	dune build -j 4 -p variantslib
    dh_auto_test -O--buildsystem=ocaml_dune
-	dune runtest -j 3 -p variantslib
+	dune runtest -j 4 -p variantslib
    create-stamp debian/debhelper-build-stamp
    dh_testroot -O--buildsystem=ocaml_dune
    dh_prep -O--buildsystem=ocaml_dune
@@ -437,12 +473,14 @@
 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/31087/tmp/hooks/B01_cleanup starting
+I: user script /srv/workspace/pbuilder/31087/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/22024 and its subdirectories
-I: Current time: Fri Oct 11 02:27:13 -12 2024
-I: pbuilder-time-stamp: 1728656833
+I: removing directory /srv/workspace/pbuilder/31087 and its subdirectories
+I: Current time: Sat Oct 12 04:28:14 +14 2024
+I: pbuilder-time-stamp: 1728656894