Diff of the two buildlogs:

--
--- b1/build.log	2024-05-19 03:27:34.987525155 +0000
+++ b2/build.log	2024-05-19 03:28:25.509377015 +0000
@@ -1,6 +1,6 @@
 I: pbuilder: network access will be disabled during build
-I: Current time: Sat May 18 15:26:47 -12 2024
-I: pbuilder-time-stamp: 1716089207
+I: Current time: Sat Jun 21 23:50:37 +14 2025
+I: pbuilder-time-stamp: 1750499437
 I: Building the build Environment
 I: extracting base tarball [/var/cache/pbuilder/unstable-reproducible-base.tgz]
 I: copying local configuration
@@ -25,52 +25,84 @@
 dpkg-source: info: unpacking golang-github-caarlos0-env_6.7.1-1.debian.tar.xz
 I: Not using root during the build.
 I: Installing the build-deps
-I: user script /srv/workspace/pbuilder/4024891/tmp/hooks/D02_print_environment starting
+I: user script /srv/workspace/pbuilder/2890239/tmp/hooks/D01_modify_environment starting
+debug: Running on codethink01-arm64.
+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 Jun 21 09:50 /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/2890239/tmp/hooks/D01_modify_environment finished
+I: user script /srv/workspace/pbuilder/2890239/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='arm64'
-  DEBIAN_FRONTEND='noninteractive'
+  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]="21" [3]="1" [4]="release" [5]="aarch64-unknown-linux-gnu")
+  BASH_VERSION='5.2.21(1)-release'
+  BUILDDIR=/build/reproducible-path
+  BUILDUSERGECOS='second user,second room,second work-phone,second home-phone,second other'
+  BUILDUSERNAME=pbuilder2
+  BUILD_ARCH=arm64
+  DEBIAN_FRONTEND=noninteractive
   DEB_BUILD_OPTIONS='buildinfo=+all reproducible=+all parallel=12 '
-  DISTRIBUTION='unstable'
-  HOME='/root'
-  HOST_ARCH='arm64'
+  DIRSTACK=()
+  DISTRIBUTION=unstable
+  EUID=0
+  FUNCNAME=([0]="Echo" [1]="main")
+  GROUPS=()
+  HOME=/root
+  HOSTNAME=i-capture-the-hostname
+  HOSTTYPE=aarch64
+  HOST_ARCH=arm64
   IFS=' 	
   '
-  INVOCATION_ID='58017435826e4cc9b4a8cdad807cc062'
-  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='4024891'
-  PS1='# '
-  PS2='> '
+  INVOCATION_ID=7c4db800c24e4a8a97947b714ad67fd7
+  LANG=C
+  LANGUAGE=nl_BE:nl
+  LC_ALL=C
+  MACHTYPE=aarch64-unknown-linux-gnu
+  MAIL=/var/mail/root
+  OPTERR=1
+  OPTIND=1
+  OSTYPE=linux-gnu
+  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=2890239
   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.Hc5UD1OI/pbuilderrc_mJuq --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.Hc5UD1OI/b1 --logfile b1/build.log golang-github-caarlos0-env_6.7.1-1.dsc'
-  SUDO_GID='109'
-  SUDO_UID='104'
-  SUDO_USER='jenkins'
-  TERM='unknown'
-  TZ='/usr/share/zoneinfo/Etc/GMT+12'
-  USER='root'
-  _='/usr/bin/systemd-run'
-  http_proxy='http://192.168.101.4:3128'
+  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.Hc5UD1OI/pbuilderrc_4zOl --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.Hc5UD1OI/b2 --logfile b2/build.log golang-github-caarlos0-env_6.7.1-1.dsc'
+  SUDO_GID=109
+  SUDO_UID=104
+  SUDO_USER=jenkins
+  TERM=unknown
+  TZ=/usr/share/zoneinfo/Etc/GMT-14
+  UID=0
+  USER=root
+  _='I: set'
+  http_proxy=http://192.168.101.4:3128
 I: uname -a
-  Linux codethink04-arm64 6.1.0-21-cloud-arm64 #1 SMP Debian 6.1.90-1 (2024-05-03) aarch64 GNU/Linux
+  Linux i-capture-the-hostname 6.1.0-21-cloud-arm64 #1 SMP Debian 6.1.90-1 (2024-05-03) aarch64 GNU/Linux
 I: ls -l /bin
-  lrwxrwxrwx 1 root root 7 May 17 07:42 /bin -> usr/bin
-I: user script /srv/workspace/pbuilder/4024891/tmp/hooks/D02_print_environment finished
+  lrwxrwxrwx 1 root root 7 Jun 19 14:05 /bin -> usr/bin
+I: user script /srv/workspace/pbuilder/2890239/tmp/hooks/D02_print_environment finished
  -> Attempting to satisfy build-dependencies
  -> Creating pbuilder-satisfydepends-dummy package
 Package: pbuilder-satisfydepends-dummy
@@ -364,7 +396,11 @@
 Building tag database...
  -> Finished parsing the build-deps
 I: Building the package
-I: Running cd /build/reproducible-path/golang-github-caarlos0-env-6.7.1/ && 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  > ../golang-github-caarlos0-env_6.7.1-1_source.changes
+I: user script /srv/workspace/pbuilder/2890239/tmp/hooks/A99_set_merged_usr starting
+Not re-configuring usrmerge for unstable
+I: user script /srv/workspace/pbuilder/2890239/tmp/hooks/A99_set_merged_usr finished
+hostname: Name or service not known
+I: Running cd /build/reproducible-path/golang-github-caarlos0-env-6.7.1/ && 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  > ../golang-github-caarlos0-env_6.7.1-1_source.changes
 dpkg-buildpackage: info: source package golang-github-caarlos0-env
 dpkg-buildpackage: info: source version 6.7.1-1
 dpkg-buildpackage: info: source distribution unstable
@@ -383,30 +419,30 @@
    dh_auto_configure -O--buildsystem=golang
    dh_auto_build -O--buildsystem=golang
 	cd obj-aarch64-linux-gnu && go install -trimpath -v -p 12 github.com/caarlos0/env
-internal/godebugs
-internal/unsafeheader
+encoding
+internal/itoa
 internal/goarch
 unicode/utf8
-internal/goos
-internal/coverage/rtcov
-internal/abi
-math/bits
 internal/goexperiment
 internal/chacha8rand
-encoding
-runtime/internal/sys
-runtime/internal/math
-internal/itoa
+runtime/internal/syscall
 internal/cpu
+internal/unsafeheader
+internal/goos
+math/bits
+internal/coverage/rtcov
+internal/godebugs
+runtime/internal/math
+internal/abi
 internal/race
-runtime/internal/syscall
 sync/atomic
-cmp
 unicode
-slices
+runtime/internal/sys
+cmp
 math
-runtime/internal/atomic
+slices
 internal/bytealg
+runtime/internal/atomic
 runtime
 internal/reflectlite
 sync
@@ -422,11 +458,11 @@
 strings
 reflect
 internal/syscall/unix
-time
 internal/syscall/execenv
-internal/fmtsort
+time
 internal/poll
 io/fs
+internal/fmtsort
 os
 fmt
 io/ioutil
@@ -583,7 +619,7 @@
 === RUN   ExampleParseWithFuncs
 --- PASS: ExampleParseWithFuncs (0.00s)
 PASS
-ok  	github.com/caarlos0/env	0.017s
+ok  	github.com/caarlos0/env	0.012s
    create-stamp debian/debhelper-build-stamp
    dh_testroot -O--buildsystem=golang
    dh_prep -O--buildsystem=golang
@@ -610,12 +646,14 @@
 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/2890239/tmp/hooks/B01_cleanup starting
+I: user script /srv/workspace/pbuilder/2890239/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/4024891 and its subdirectories
-I: Current time: Sat May 18 15:27:33 -12 2024
-I: pbuilder-time-stamp: 1716089253
+I: removing directory /srv/workspace/pbuilder/2890239 and its subdirectories
+I: Current time: Sat Jun 21 23:51:23 +14 2025
+I: pbuilder-time-stamp: 1750499483