install packages with explicit TMPDIR

For package installation, the runner $TMPDIR may not be big enough, eg
when rebuilding an initramfs it runs out of space, so use a new function
that sets it explicitly.

test/borg.bats

 load common
 
 begin_borg() {
-    apt-get -qq install debootstrap borgbackup
+    install_pkgs debootstrap borgbackup
     if [ ! -d "$BN_SRCDIR" ]; then
         debootstrap --variant=minbase testing "$BN_SRCDIR"
     fi

test/common.bash

@@ -241,3 +241,7 @@ makegpgkeys() {
     BN_SIGNKEY=$(gpg --keyid-format long -k sign@bntest0 | sed -n '2p' | grep -o '\S\+')
     export BN_SIGNKEY
 }
+
+install_pkgs() {
+    TMPDIR=/tmp DEBIAN_FRONTEND=noninteractive apt-get -qq install $@
+}

test/dup.bats

 load common
 
 begin_dup() {
-    apt-get -qq install debootstrap duplicity trickle
+    install_pkgs debootstrap duplicity trickle
     if [ ! -d /var/cache/bntest ]; then
         debootstrap --variant=minbase testing "$BN_SRCDIR"
     fi

test/mysql.bats

 load common
 
 begin_mysql() {
-    apt-get -qq install default-mysql-server
+    install_pkgs install default-mysql-server
     systemctl is-active mysql || systemctl start mysql
     zcat "${BATS_TEST_DIRNAME}/samples/bntest_p8Cz8k.sql.gz" | mysql --defaults-file=/etc/mysql/debian.cnf
     zcat "${BATS_TEST_DIRNAME}/samples/bntest_v11vJj.sql.gz" | mysql --defaults-file=/etc/mysql/debian.cnf

test/pgsql.bats

 load common
 
 begin_pgsql() {
-    apt-get -qq install postgresql
+    install_pkgs postgresql
     systemctl is-active postgresql || systemctl start postgresql
     sudo -u postgres createuser --superuser root
     createdb bntest_p8Cz8k

test/rdiff.bats

 load common
 
 begin_rdiff() {
-    apt-get -qq install debootstrap rdiff-backup cstream
+    install_pkgs install debootstrap rdiff-backup cstream
     if [ ! -d /var/cache/bntest ]; then
         debootstrap --variant=minbase testing /var/cache/bntest
     fi

test/rsync.bats

 load common
 
 begin_rsync() {
-    apt-get -qq install debootstrap rsync
+    install_pkgs debootstrap rsync
     if [ ! -d "$BN_SRCDIR" ]; then
         debootstrap --variant=minbase testing "$BN_SRCDIR"
     fi

test/sys.bats

 load common
 
 begin_sys() {
-    apt-get -qq install debconf-utils hwinfo lvm2 cryptsetup-bin parted
+    install_pkgs debconf-utils hwinfo lvm2 cryptsetup-bin parted
 
     cat << EOF > "${BATS_TMPDIR}/backup.d/test.sys"
 when = manual

test/tar.bats

 load common
 
 begin_tar() {
-    apt-get -qq install debootstrap ncompress zstd
+    install_pkgs debootstrap ncompress zstd
     if [ ! -d "$BN_SRCDIR" ]; then
         debootstrap --variant=minbase testing "$BN_SRCDIR"
     fi