reproducible Debian: always bootstrap schroots using mmdebstrap

Signed-off-by: Holger Levsen <holger@layer-acht.org>

bin/schroot-create.sh

 #!/bin/bash
 # vim: set noexpandtab:
 
-# Copyright © 2012-2020 Holger Levsen <holger@layer-acht.org>
+# Copyright © 2012-2022 Holger Levsen <holger@layer-acht.org>
 #           ©      2013 Antonio Terceiro <terceiro@debian.org>
 #           ©      2014 Joachim Breitner <nomeata@debian.org>
 #           © 2015-2018 Mattia Rizzolo <mattia@debian.org>
@@ -134,28 +134,12 @@ bootstrap() {
 	. /srv/jenkins/bin/jenkins_node_definitions.sh
 	get_node_information "$HOSTNAME"
 
-	# choosing bootstrapping method
 	local DEBOOTSTRAP=()
-	if command -v mmdebstrap >/dev/null ; then
-		# not available on Ubuntu 16.04 LTS
-		DEBOOTSTRAP+=(mmdebstrap)
-		if "$NODE_RUN_IN_THE_FUTURE" ; then
-			# configure apt to ignore expired release files
-			echo "This node is reported to run in the future, configuring APT to ignore the Release file expiration..."
-			DEBOOTSTRAP+=(--aptopt='Acquire::Check-Valid-Until "false"')
-		fi
-	else
-		DEBOOTSTRAP+=(debootstrap)
-		# configure dpkg to be faster (mmdebstrap expects an empty directory and is fast by design)
-		mkdir -p "$SCHROOT_TARGET/etc/dpkg/dpkg.cfg.d"
-		echo force-unsafe-io > "$SCHROOT_TARGET/etc/dpkg/dpkg.cfg.d/02dpkg-unsafe-io"
-		if "$NODE_RUN_IN_THE_FUTURE" ; then
-			# configure apt to ignore expired release files
-			echo "This node is reported to run in the future, configuring APT to ignore the Release file expiration..."
-			mkdir -p "$SCHROOT_TARGET/etc/apt/apt.conf.d/"
-			echo 'Acquire::Check-Valid-Until "false";' | sudo tee -a "$SCHROOT_TARGET"/etc/apt/apt.conf.d/398future >/dev/null
-		fi
-
+	DEBOOTSTRAP+=(mmdebstrap)
+	if "$NODE_RUN_IN_THE_FUTURE" ; then
+		# configure apt to ignore expired release files
+		echo "This node is reported to run in the future, configuring APT to ignore the Release file expiration..."
+		DEBOOTSTRAP+=(--aptopt='Acquire::Check-Valid-Until "false"')
 	fi
 	set -x
 	sudo -- "${DEBOOTSTRAP[@]}" "$SUITE" "$SCHROOT_TARGET" "$MIRROR" | tee "$TMPLOG"