Diff of the two buildlogs:

--
--- b1/build.log	2025-01-27 00:37:32.883177940 +0000
+++ b2/build.log	2025-01-27 00:40:58.485926786 +0000
@@ -1,6 +1,6 @@
 I: pbuilder: network access will be disabled during build
-I: Current time: Sat Feb 28 18:59:50 -12 2026
-I: pbuilder-time-stamp: 1772348390
+I: Current time: Mon Jan 27 14:37:36 +14 2025
+I: pbuilder-time-stamp: 1737938256
 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 rust-sync-wrapper_1.0.2-1.debian.tar.xz
 I: Not using root during the build.
 I: Installing the build-deps
-I: user script /srv/workspace/pbuilder/3139210/tmp/hooks/D02_print_environment starting
+I: user script /srv/workspace/pbuilder/3929186/tmp/hooks/D01_modify_environment starting
+debug: Running on ionos11-amd64.
+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 27 00:37 /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/3929186/tmp/hooks/D01_modify_environment finished
+I: user script /srv/workspace/pbuilder/3929186/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='amd64'
-  DEBIAN_FRONTEND='noninteractive'
-  DEB_BUILD_OPTIONS='buildinfo=+all reproducible=+all parallel=42 '
-  DISTRIBUTION='unstable'
-  HOME='/root'
-  HOST_ARCH='amd64'
+  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]="x86_64-pc-linux-gnu")
+  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=amd64
+  DEBIAN_FRONTEND=noninteractive
+  DEB_BUILD_OPTIONS='buildinfo=+all reproducible=+all parallel=20 '
+  DIRSTACK=()
+  DISTRIBUTION=unstable
+  EUID=0
+  FUNCNAME=([0]="Echo" [1]="main")
+  GROUPS=()
+  HOME=/root
+  HOSTNAME=i-capture-the-hostname
+  HOSTTYPE=x86_64
+  HOST_ARCH=amd64
   IFS=' 	
   '
-  INVOCATION_ID='2bec3b85dd5e49de813c299bca17e919'
-  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='3139210'
-  PS1='# '
-  PS2='> '
+  INVOCATION_ID=c8187dc72e1146f18664155621cec95d
+  LANG=C
+  LANGUAGE=et_EE:et
+  LC_ALL=C
+  MACHTYPE=x86_64-pc-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=3929186
   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.IoQB1q6Y/pbuilderrc_kXMx --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.IoQB1q6Y/b1 --logfile b1/build.log rust-sync-wrapper_1.0.2-1.dsc'
-  SUDO_GID='111'
-  SUDO_UID='106'
-  SUDO_USER='jenkins'
-  TERM='unknown'
-  TZ='/usr/share/zoneinfo/Etc/GMT+12'
-  USER='root'
-  _='/usr/bin/systemd-run'
-  http_proxy='http://213.165.73.152:3128'
+  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.IoQB1q6Y/pbuilderrc_KJRI --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.IoQB1q6Y/b2 --logfile b2/build.log rust-sync-wrapper_1.0.2-1.dsc'
+  SUDO_GID=111
+  SUDO_UID=106
+  SUDO_USER=jenkins
+  TERM=unknown
+  TZ=/usr/share/zoneinfo/Etc/GMT-14
+  UID=0
+  USER=root
+  _='I: set'
+  http_proxy=http://46.16.76.132:3128
 I: uname -a
-  Linux ionos15-amd64 6.12.9+bpo-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.12.9-1~bpo12+1 (2025-01-19) x86_64 GNU/Linux
+  Linux i-capture-the-hostname 6.1.0-30-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.124-1 (2025-01-12) x86_64 GNU/Linux
 I: ls -l /bin
-  lrwxrwxrwx 1 root root 7 Nov 22  2024 /bin -> usr/bin
-I: user script /srv/workspace/pbuilder/3139210/tmp/hooks/D02_print_environment finished
+  lrwxrwxrwx 1 root root 7 Nov 22 14:40 /bin -> usr/bin
+I: user script /srv/workspace/pbuilder/3929186/tmp/hooks/D02_print_environment finished
  -> Attempting to satisfy build-dependencies
  -> Creating pbuilder-satisfydepends-dummy package
 Package: pbuilder-satisfydepends-dummy
@@ -185,7 +217,7 @@
 Get: 74 http://deb.debian.org/debian unstable/main amd64 po-debconf all 1.0.21+nmu1 [248 kB]
 Get: 75 http://deb.debian.org/debian unstable/main amd64 debhelper all 13.24.1 [920 kB]
 Get: 76 http://deb.debian.org/debian unstable/main amd64 dh-cargo all 31 [10.3 kB]
-Fetched 137 MB in 2s (62.5 MB/s)
+Fetched 137 MB in 6s (23.7 MB/s)
 Preconfiguring packages ...
 Selecting previously unselected package libpython3.13-minimal:amd64.
 (Reading database ... 
(Reading database ... 5%
(Reading database ... 10%
(Reading database ... 15%
(Reading database ... 20%
(Reading database ... 25%
(Reading database ... 30%
(Reading database ... 35%
(Reading database ... 40%
(Reading database ... 45%
(Reading database ... 50%
(Reading database ... 55%
(Reading database ... 60%
(Reading database ... 65%
(Reading database ... 70%
(Reading database ... 75%
(Reading database ... 80%
(Reading database ... 85%
(Reading database ... 90%
(Reading database ... 95%
(Reading database ... 100%
(Reading database ... 19832 files and directories currently installed.)
@@ -448,8 +480,8 @@
 Setting up tzdata (2025a-1) ...
 
 Current default time zone: 'Etc/UTC'
-Local time is now:      Sun Mar  1 07:00:22 UTC 2026.
-Universal Time is now:  Sun Mar  1 07:00:22 UTC 2026.
+Local time is now:      Mon Jan 27 00:40:11 UTC 2025.
+Universal Time is now:  Mon Jan 27 00:40:11 UTC 2025.
 Run 'dpkg-reconfigure tzdata' if you wish to change it.
 
 Setting up autotools-dev (20220109.1) ...
@@ -516,7 +548,11 @@
 Building tag database...
  -> Finished parsing the build-deps
 I: Building the package
-I: Running cd /build/reproducible-path/rust-sync-wrapper-1.0.2/ && 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  > ../rust-sync-wrapper_1.0.2-1_source.changes
+I: user script /srv/workspace/pbuilder/3929186/tmp/hooks/A99_set_merged_usr starting
+Not re-configuring usrmerge for unstable
+I: user script /srv/workspace/pbuilder/3929186/tmp/hooks/A99_set_merged_usr finished
+hostname: Name or service not known
+I: Running cd /build/reproducible-path/rust-sync-wrapper-1.0.2/ && 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  > ../rust-sync-wrapper_1.0.2-1_source.changes
 dpkg-buildpackage: info: source package rust-sync-wrapper
 dpkg-buildpackage: info: source version 1.0.2-1
 dpkg-buildpackage: info: source distribution unstable
@@ -526,7 +562,7 @@
  debian/rules clean
 dh clean --buildsystem cargo
    dh_auto_clean -O--buildsystem=cargo
-debian cargo wrapper: options, profiles, parallel, lto: ['buildinfo=+all', 'reproducible=+all', 'parallel=42'] [] ['-j42'] 
+debian cargo wrapper: options, profiles, parallel, lto: ['buildinfo=+all', 'reproducible=+all', 'parallel=20'] [] ['-j20'] 
 debian cargo wrapper: rust_type, gnu_type: x86_64-unknown-linux-gnu, x86_64-linux-gnu
 debian cargo wrapper: running subprocess (['env', 'RUST_BACKTRACE=1', '/usr/bin/cargo', 'clean', '--verbose', '--verbose'],) {'check': True}
      Removed 0 files
@@ -537,17 +573,17 @@
    dh_update_autotools_config -O--buildsystem=cargo
    dh_autoreconf -O--buildsystem=cargo
    dh_auto_configure -O--buildsystem=cargo
-debian cargo wrapper: options, profiles, parallel, lto: ['buildinfo=+all', 'reproducible=+all', 'parallel=42'] [] ['-j42'] 
+debian cargo wrapper: options, profiles, parallel, lto: ['buildinfo=+all', 'reproducible=+all', 'parallel=20'] [] ['-j20'] 
 debian cargo wrapper: rust_type, gnu_type: x86_64-unknown-linux-gnu, x86_64-linux-gnu
 debian cargo wrapper: linking /usr/share/cargo/registry/* into /build/reproducible-path/rust-sync-wrapper-1.0.2/debian/cargo_registry/
    dh_auto_build -O--buildsystem=cargo
    dh_auto_test -O--buildsystem=cargo
-debian cargo wrapper: options, profiles, parallel, lto: ['buildinfo=+all', 'reproducible=+all', 'parallel=42'] [] ['-j42'] 
+debian cargo wrapper: options, profiles, parallel, lto: ['buildinfo=+all', 'reproducible=+all', 'parallel=20'] [] ['-j20'] 
 debian cargo wrapper: rust_type, gnu_type: x86_64-unknown-linux-gnu, x86_64-linux-gnu
-debian cargo wrapper: running subprocess (['env', 'RUST_BACKTRACE=1', '/usr/bin/cargo', '-Zavoid-dev-deps', 'build', '--verbose', '--verbose', '-j42', '--target', 'x86_64-unknown-linux-gnu'],) {}
+debian cargo wrapper: running subprocess (['env', 'RUST_BACKTRACE=1', '/usr/bin/cargo', '-Zavoid-dev-deps', 'build', '--verbose', '--verbose', '-j20', '--target', 'x86_64-unknown-linux-gnu'],) {}
    Compiling sync_wrapper v1.0.2 (/build/reproducible-path/rust-sync-wrapper-1.0.2)
      Running `CARGO=/usr/bin/cargo CARGO_CRATE_NAME=sync_wrapper CARGO_MANIFEST_DIR=/build/reproducible-path/rust-sync-wrapper-1.0.2 CARGO_MANIFEST_PATH=/build/reproducible-path/rust-sync-wrapper-1.0.2/Cargo.toml CARGO_PKG_AUTHORS='Actyx AG <developer@actyx.io>' CARGO_PKG_DESCRIPTION='A tool for enlisting the compiler'\''s help in proving the absence of concurrency' CARGO_PKG_HOMEPAGE='https://docs.rs/sync_wrapper' CARGO_PKG_LICENSE=Apache-2.0 CARGO_PKG_LICENSE_FILE='' CARGO_PKG_NAME=sync_wrapper CARGO_PKG_README=README.md CARGO_PKG_REPOSITORY='https://github.com/Actyx/sync_wrapper' CARGO_PKG_RUST_VERSION='' CARGO_PKG_VERSION=1.0.2 CARGO_PKG_VERSION_MAJOR=1 CARGO_PKG_VERSION_MINOR=0 CARGO_PKG_VERSION_PATCH=2 CARGO_PKG_VERSION_PRE='' CARGO_PRIMARY_PACKAGE=1 LD_LIBRARY_PATH=/build/reproducible-path/rust-sync-wrapper-1.0.2/target/debug/deps rustc --crate-name sync_wrapper --edition=2021 src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 --check-cfg 'cfg(docsrs)' --check-cfg 'cfg(feature, values("futures", "futures-core"))' -C metadata=9b5072c786696561 -C extra-filename=-9b5072c786696561 --out-dir /build/reproducible-path/rust-sync-wrapper-1.0.2/target/x86_64-unknown-linux-gnu/debug/deps --target x86_64-unknown-linux-gnu -C incremental=/build/reproducible-path/rust-sync-wrapper-1.0.2/target/x86_64-unknown-linux-gnu/debug/incremental -L dependency=/build/reproducible-path/rust-sync-wrapper-1.0.2/target/x86_64-unknown-linux-gnu/debug/deps -L dependency=/build/reproducible-path/rust-sync-wrapper-1.0.2/target/debug/deps -C debuginfo=2 -C strip=none --cap-lints warn -C linker=x86_64-linux-gnu-gcc -C link-arg=-Wl,-z,relro --remap-path-prefix /build/reproducible-path/rust-sync-wrapper-1.0.2=/usr/share/cargo/registry/sync-wrapper-1.0.2 --remap-path-prefix /build/reproducible-path/rust-sync-wrapper-1.0.2/debian/cargo_registry=/usr/share/cargo/registry`
-    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.21s
+    Finished `dev` profile [unoptimized + debuginfo] target(s) in 1.21s
 rustc 1.84.0+dfsg1-2 1
    create-stamp debian/debhelper-build-stamp
    dh_testroot -O--buildsystem=cargo
@@ -578,12 +614,14 @@
 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/3929186/tmp/hooks/B01_cleanup starting
+I: user script /srv/workspace/pbuilder/3929186/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/3139210 and its subdirectories
-I: Current time: Sat Feb 28 19:00:29 -12 2026
-I: pbuilder-time-stamp: 1772348429
+I: removing directory /srv/workspace/pbuilder/3929186 and its subdirectories
+I: Current time: Mon Jan 27 14:40:57 +14 2025
+I: pbuilder-time-stamp: 1737938457