diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index b229739be8..fe8155772a 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -405,13 +405,11 @@ jobs:
         - jobname: linux-sha256
           image: ubuntu:rolling
           cc: clang
-        - jobname: linux-reftable
+        - jobname: linux-reftable-sha256
           image: ubuntu:rolling
           cc: clang
-        - jobname: linux-TEST-vars
-          image: ubuntu:20.04
-          cc: gcc
-          cc_package: gcc-8
+        - jobname: linux-feature-testbed
+          image: ubuntu:latest
         - jobname: linux-breaking-changes
           cc: gcc
           image: ubuntu:rolling
@@ -431,9 +429,8 @@ jobs:
           cc: gcc
         - jobname: linux-musl-meson
           image: alpine:latest
-        # Supported until 2025-04-02.
         - jobname: linux32
-          image: i386/ubuntu:20.04
+          image: i386/debian:latest
         # A RHEL 8 compatible distro.  Supported until 2029-05-31.
         - jobname: almalinux-8
           image: almalinux:8
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 3f24835500..9b7698a003 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -39,13 +39,11 @@ test:linux:
       - jobname: linux-sha256
         image: ubuntu:rolling
         CC: clang
-      - jobname: linux-reftable
+      - jobname: linux-reftable-sha256
         image: ubuntu:rolling
         CC: clang
-      - jobname: linux-TEST-vars
-        image: ubuntu:20.04
-        CC: gcc
-        CC_PACKAGE: gcc-8
+      - jobname: linux-feature-testbed
+        image: ubuntu:latest
       - jobname: linux-breaking-changes
         image: ubuntu:rolling
         CC: gcc
@@ -65,9 +63,8 @@ test:linux:
         CC: gcc
       - jobname: linux-musl-meson
         image: alpine:latest
-        # Supported until 2025-04-02.
       - jobname: linux32
-        image: i386/ubuntu:20.04
+        image: i386/debian:latest
       # A RHEL 8 compatible distro.  Supported until 2029-05-31.
       - jobname: almalinux-8
         image: almalinux:8
diff --git a/ci/install-dependencies.sh b/ci/install-dependencies.sh
index d57dce5663..4b1733ad15 100755
--- a/ci/install-dependencies.sh
+++ b/ci/install-dependencies.sh
@@ -39,7 +39,7 @@ fedora-*|almalinux-*)
 	dnf -yq update >/dev/null &&
 	dnf -yq install shadow-utils sudo make pkg-config gcc findutils diffutils perl python3 gawk gettext zlib-devel expat-devel openssl-devel curl-devel pcre2-devel $MESON_DEPS cargo >/dev/null
 	;;
-ubuntu-*|i386/ubuntu-*|debian-*)
+ubuntu-*|i386/debian-*|debian-*)
 	# Required so that apt doesn't wait for user input on certain packages.
 	export DEBIAN_FRONTEND=noninteractive
 
@@ -48,10 +48,6 @@ ubuntu-*|i386/ubuntu-*|debian-*)
 		SVN='libsvn-perl subversion'
 		LANGUAGES='language-pack-is'
 		;;
-	i386/ubuntu-*)
-		SVN=
-		LANGUAGES='language-pack-is'
-		;;
 	*)
 		SVN='libsvn-perl subversion'
 		LANGUAGES='locales-all'
@@ -65,7 +61,7 @@ ubuntu-*|i386/ubuntu-*|debian-*)
 		tcl tk gettext zlib1g-dev perl-modules liberror-perl libauthen-sasl-perl \
 		libemail-valid-perl libio-pty-perl libio-socket-ssl-perl libnet-smtp-ssl-perl libdbd-sqlite3-perl libcgi-pm-perl \
 		libsecret-1-dev libpcre2-dev meson ninja-build pkg-config cargo \
-		${CC_PACKAGE:-${CC:-gcc}} $PYTHON_PACKAGE
+		${CC_PACKAGE:-${CC:-gcc}} python3
 
 	# Starting with Ubuntu 25.10, sudo can now be provided via either
 	# sudo(1) or sudo-rs(1), with the latter being the default. The problem
diff --git a/ci/lib.sh b/ci/lib.sh
index ca80ea7bde..2e63d65254 100755
--- a/ci/lib.sh
+++ b/ci/lib.sh
@@ -259,7 +259,7 @@ then
 
 		CI_OS_NAME=osx
 		;;
-	*,almalinux:*|*,alpine:*|*,debian:*|*,fedora:*|*,ubuntu:*|*,i386/ubuntu:*)
+	*,almalinux:*|*,alpine:*|*,debian:*|*,fedora:*|*,ubuntu:*|*,i386/debian:*)
 		CI_OS_NAME=linux
 		;;
 	*)
@@ -344,16 +344,7 @@ esac
 
 case "$distro" in
 ubuntu-*)
-	# Python 2 is end of life, and Ubuntu 23.04 and newer don't actually
-	# have it anymore. We thus only test with Python 2 on older LTS
-	# releases.
-	if test "$distro" = "ubuntu-20.04"
-	then
-		PYTHON_PACKAGE=python2
-	else
-		PYTHON_PACKAGE=python3
-	fi
-	MAKEFLAGS="$MAKEFLAGS PYTHON_PATH=/usr/bin/$PYTHON_PACKAGE"
+	MAKEFLAGS="$MAKEFLAGS PYTHON_PATH=/usr/bin/python3"
 
 	export GIT_TEST_HTTPD=true
 
diff --git a/ci/run-build-and-tests.sh b/ci/run-build-and-tests.sh
index 6a3b43b366..68b91e3143 100755
--- a/ci/run-build-and-tests.sh
+++ b/ci/run-build-and-tests.sh
@@ -18,11 +18,11 @@ almalinux-*|debian-*|fedora-*|linux-*)
 esac
 
 case "$jobname" in
-fedora-breaking-changes-musl|linux-breaking-changes)
+fedora-breaking-changes-meson|linux-breaking-changes)
 	export WITH_BREAKING_CHANGES=YesPlease
 	MESONFLAGS="$MESONFLAGS -Dbreaking_changes=true"
 	;;
-linux-TEST-vars)
+linux-feature-testbed)
 	export OPENSSL_SHA1_UNSAFE=YesPlease
 	export GIT_TEST_SPLIT_INDEX=yes
 	export GIT_TEST_FULL_IN_PACK_ARRAY=true
@@ -37,17 +37,16 @@ linux-TEST-vars)
 	export GIT_TEST_CHECKOUT_WORKERS=2
 	export GIT_TEST_PACK_USE_BITMAP_BOUNDARY_TRAVERSAL=1
 	;;
-linux-clang)
-	export NO_RUST=UnfortunatelyYes
-	export GIT_TEST_DEFAULT_HASH=sha1
-	;;
 linux-sha256)
 	export GIT_TEST_DEFAULT_HASH=sha256
 	;;
-linux-reftable|linux-reftable-leaks|osx-reftable)
+linux-reftable-sha256)
+	export GIT_TEST_DEFAULT_REF_STORAGE_FORMAT=reftable
+	export GIT_TEST_DEFAULT_HASH=sha256
+	;;
+linux-reftable-leaks|osx-reftable)
 	export GIT_TEST_DEFAULT_REF_STORAGE_FORMAT=reftable
 	;;
-
 esac
 
 case "$jobname" in
diff --git a/t/t5004-archive-corner-cases.sh b/t/t5004-archive-corner-cases.sh
index 768b0ff85d..13edfbe5bc 100755
--- a/t/t5004-archive-corner-cases.sh
+++ b/t/t5004-archive-corner-cases.sh
@@ -187,25 +187,31 @@ test_expect_success EXPENSIVE,UNZIP,UNZIP_ZIP64_SUPPORT \
 
 test_expect_success EXPENSIVE,LONG_IS_64BIT,UNZIP,UNZIP_ZIP64_SUPPORT,ZIPINFO \
 	'zip archive with files bigger than 4GB' '
-	# Pack created with:
-	#   dd if=/dev/zero of=file bs=1M count=4100 && git hash-object -w file
-	mkdir -p .git/objects/pack &&
+	test_when_finished rm -rf big-file &&
+	git init --object-format=sha1 big-file &&
 	(
-		cd .git/objects/pack &&
-		"$GIT_UNZIP" "$TEST_DIRECTORY"/t5004/big-pack.zip
-	) &&
-	blob=754a93d6fada4c6873360e6cb4b209132271ab0e &&
-	size=$(expr 4100 "*" 1024 "*" 1024) &&
+		cd big-file &&
 
-	# create a tree containing the file
-	tree=$(echo "100644 blob $blob	big-file" | git mktree) &&
+		# Pack created with:
+		#   dd if=/dev/zero of=file bs=1M count=4100 && git hash-object -w file
+		mkdir -p .git/objects/pack &&
+		(
+			cd .git/objects/pack &&
+			"$GIT_UNZIP" "$TEST_DIRECTORY"/t5004/big-pack.zip
+		) &&
+		blob=754a93d6fada4c6873360e6cb4b209132271ab0e &&
+		size=$(expr 4100 "*" 1024 "*" 1024) &&
 
-	# zip it, creating an archive with a file bigger than 4GB
-	git archive -o big.zip $tree &&
+		# create a tree containing the file
+		tree=$(echo "100644 blob $blob	big-file" | git mktree) &&
 
-	"$GIT_UNZIP" -t big.zip &&
-	"$ZIPINFO" big.zip >big.lst &&
-	test_grep $size big.lst
+		# zip it, creating an archive with a file bigger than 4GB
+		git archive -o big.zip $tree &&
+
+		"$GIT_UNZIP" -t big.zip &&
+		"$ZIPINFO" big.zip >big.lst &&
+		test_grep $size big.lst
+	)
 '
 
 build_tree() {