Put TMPDIR on /var/tmp by default

Resolves: rhbz1988420

rear-tmpdir.patch

@@ -0,0 +1,37 @@
+diff --git a/usr/share/rear/conf/default.conf b/usr/share/rear/conf/default.conf
+index 9ada92c3..3bdb5497 100644
+--- a/usr/share/rear/conf/default.conf
++++ b/usr/share/rear/conf/default.conf
+@@ -57,10 +57,16 @@
+ #
+ # where /prefix/for/rear/working/directory must already exist.
+ # This is useful for example when there is not sufficient free space
+-# in /tmp or $TMPDIR for the ISO image or even the backup archive.
+-# TMPDIR cannot be set to a default value here, otherwise /usr/sbin/rear
++# in /var/tmp or $TMPDIR for the ISO image or even the backup archive.
++# TMPDIR cannot be set to a default value here unconditionally but only
++# if it is not set before calling the program, otherwise /usr/sbin/rear
+ # would not work in compliance with the Linux/Unix standards regarding TMPDIR
+ # see https://github.com/rear/rear/issues/968
++# The default is /var/tmp instead of the more usual /tmp (the system default),
++# because /tmp is not intended for such large amounts of data that ReaR usually
++# produces when creating the image (see file-hierarchy(7)). In particular,
++# /tmp can be a tmpfs, and thus restricted by the available RAM/swap.
++export TMPDIR="${TMPDIR-/var/tmp}"
+ 
+ ##
+ # ROOT_HOME_DIR
+diff --git a/usr/share/rear/rescue/GNU/Linux/600_unset_TMPDIR_in_rescue_conf.sh b/usr/share/rear/rescue/GNU/Linux/600_unset_TMPDIR_in_rescue_conf.sh
+deleted file mode 100644
+index 84d0cabb..00000000
+--- a/usr/share/rear/rescue/GNU/Linux/600_unset_TMPDIR_in_rescue_conf.sh
++++ /dev/null
+@@ -1,8 +0,0 @@
+-cat - <<EOF >> "$ROOTFS_DIR/etc/rear/rescue.conf"
+-# TMPDIR variable may be defined in local.conf file as prefix dir for mktemp command
+-# e.g. by defining TMPDIR=/var we would get our BUILD_DIR=/var/tmp/rear.XXXXXXXXXXXX
+-# However, in rescue we want our BUILD_DIR=/tmp/rear.XXXXXXX as we are not sure that
+-# the user defined TMPDIR would exist in our rescue image
+-# by 'unset TMPDIR' we achieve above goal (as rescue.conf is read after local.conf)!
+-unset TMPDIR
+-EOF

rear.spec

@@ -18,6 +18,7 @@ Patch0: 0001-skip-kernel-buildin-modules.patch
 Patch4:  rear-bz1492177-warning.patch
 Patch29: rear-bz1832394.patch
 Patch30: rear-sfdc02772301.patch
+Patch34: rear-tmpdir.patch
 
 # rear contains only bash scripts plus documentation so that on first glance it could be "BuildArch: noarch"
 # but actually it is not "noarch" because it only works on those architectures that are explicitly supported.