set DPkg::Chroot-Directory in APT_CONFIG

This is so that users calling apt-get install from a hook only need to
have APT_CONFIG=$MMDEBSTRAP_APT_CONFIG set and do not also have to pass
-oDPkg::Chroot-Directory="$1".

This breaks users running apt-get with
DPkg::Options::=--force-script-chrootless or with Dpkg::Pre-Install-Pkgs
from within a hook with APT_CONFIG=$MMDEBSTRAP_APT_CONFIG.

In those situations, DPkg::Chroot-Directory has to be set to the empty
string explicitly with -o to overwrite the APT_CONFIG setting.

Thanks: Helmut Grohne

hooks/merged-usr/essential00.sh

@@ -10,6 +10,7 @@ TARGET="$1"
 
 if [ "${MMDEBSTRAP_MODE:-}" = "chrootless" ]; then
 	APT_CONFIG=$MMDEBSTRAP_APT_CONFIG apt-get --yes install \
+		-oDPkg::Chroot-Directory= \
 		-oDPkg::Options::=--force-not-root \
 		-oDPkg::Options::=--force-script-chrootless \
 		-oDPkg::Options::=--root="$TARGET" \
@@ -20,7 +21,7 @@ if [ "${MMDEBSTRAP_MODE:-}" = "chrootless" ]; then
 	dpkg-query --showformat '${Source}\n' --show usr-is-merged | grep -q '^usrmerge$'
 	dpkg --compare-versions "1" "lt" "$(dpkg-query --showformat '${Version}\n' --show usr-is-merged)"
 else
-	APT_CONFIG=$MMDEBSTRAP_APT_CONFIG apt-get --yes install -oDPkg::Chroot-Directory="$TARGET" usr-is-merged
+	APT_CONFIG=$MMDEBSTRAP_APT_CONFIG apt-get --yes install usr-is-merged
 	chroot "$TARGET" dpkg-query --showformat '${db:Status-Status}\n' --show usr-is-merged | grep -q '^installed$'
 	chroot "$TARGET" dpkg-query --showformat '${Source}\n' --show usr-is-merged | grep -q '^usrmerge$'
 	dpkg --compare-versions "1" "lt" "$(chroot "$TARGET" dpkg-query --showformat '${Version}\n' --show usr-is-merged)"

mmdebstrap

@@ -1116,6 +1116,8 @@ sub run_apt_download_progress {
                         "-oDebug::NoLocking=1",
                         # no need for pty magic if we write no log
                         "-oDpkg::Use-Pty=0",
+                        # unset this or otherwise "cat >&$fd" will fail
+                        "-oDPkg::Chroot-Directory=",
                     ),
                     @{ $options->{APT_ARGV} },
                 ],
@@ -2022,6 +2024,7 @@ sub run_setup() {
         print $conf "Apt::Architectures \"$options->{nativearch}\";\n";
     }
     print $conf "Dir \"$options->{root}\";\n";
+    print $conf "DPkg::Chroot-Directory \"$options->{root}\";\n";
     # not needed anymore for apt 1.3 and newer
     print $conf
       "Dir::State::Status \"$options->{root}/var/lib/dpkg/status\";\n";
@@ -2878,6 +2881,7 @@ sub run_essential() {
         # Example: if the host has --path-exclude set, then this will also
         # affect the chroot. See #808203
         my @chrootless_opts = (
+            '-oDPkg::Chroot-Directory=',
             '-oDPkg::Options::=--force-not-root',
             '-oDPkg::Options::=--force-script-chrootless',
             '-oDPkg::Options::=--root=' . $options->{root},
@@ -3001,6 +3005,7 @@ sub run_install() {
     if ($options->{mode} eq 'chrootless') {
         if (scalar @pkgs_to_install > 0) {
             my @chrootless_opts = (
+                '-oDPkg::Chroot-Directory=',
                 '-oDPkg::Options::=--force-not-root',
                 '-oDPkg::Options::=--force-script-chrootless',
                 '-oDPkg::Options::=--root=' . $options->{root},
@@ -3054,8 +3059,6 @@ sub run_install() {
                             $options->{mode} eq 'fakechroot'
                             ? ('-o', 'DPkg::Install::Recursive::force=true')
                             : (),
-                            '-o',
-                            "DPkg::Chroot-Directory=$options->{root}",
                             '--yes',
                             'install'
                         ],

tests/not-having-to-install-apt-in-include-because-a-hook-did-it-before

@@ -4,6 +4,6 @@ export LC_ALL=C.UTF-8
 trap "rm -f /tmp/debian-chroot.tar" EXIT INT TERM
 {{ CMD }} --mode={{ MODE }} --variant=essential --include=apt \
 	--essential-hook='APT_CONFIG=$MMDEBSTRAP_APT_CONFIG apt-get update' \
-	--essential-hook='APT_CONFIG=$MMDEBSTRAP_APT_CONFIG apt-get --yes install -oDPkg::Chroot-Directory="$1" apt' \
+	--essential-hook='APT_CONFIG=$MMDEBSTRAP_APT_CONFIG apt-get --yes install apt' \
 	{{ DIST }} /tmp/debian-chroot.tar {{ MIRROR }}
 tar -tf /tmp/debian-chroot.tar | sort | grep -v ./var/lib/apt/extended_states | diff -u tar1.txt -