Comment # 4 on bug 1012810 from Johannes Meixner

To set TMPDIR in /etc/rear/local.conf you need to do it this way:
-------------------------------------------------------------------
export TMPDIR="/myreartmp"
-------------------------------------------------------------------

Furthermore there is the ReaR upstream issue
https://github.com/rear/rear/issues/968
which I have fixed upstream via
https://github.com/rear/rear/pull/969

Basically after removing the TMPDIR setting in default.conf
it should work in compliance with Unix standards.

See the comment about TMPDIR in the current ReaR upstream
GitHub 'master' default.conf file at
https://raw.githubusercontent.com/rear/rear/master/usr/share/rear/conf/default.conf

In general regarding what ReaR version to use see the section about
"Version upgrades with Relax-and-Recover" in
https://en.opensuse.org/SDB:Disaster_Recovery
that reads in particular (excerpts):
-------------------------------------------------------------------
When you have a working disaster recovery procedure,
do not upgrade ReaR
...
In contrast when a particular ReaR version does not work for you,
try a newer version. 
-------------------------------------------------------------------

In your case - because you already use the latest released ReaR
version - you may try to test and/or use the newest ReaR upstream
GitHub 'master' code.

Regarding how to test and/or use the newest ReaR upstream
GitHub 'master' code do the following:

As prerequirement install the 'git-core' RPM package
(at least on on openSUSE Leap that is the RPM package name
on Tumbleweed the RPM package name might be different)
so that you can use the 'git' command line tool.

How to use the currently newest ReaR GitHub master code:

Basically "git clone" it into a directory and
then run rear from within that directory like:
-----------------------------------------------------------------
# git clone https://github.com/rear/rear.git

# cd rear

# vi etc/rear/local.conf

# usr/sbin/rear -d -D mkbackup
-----------------------------------------------------------------
This way ReaR works "inside" that directory
independent of an also installed 'rear' RPM package
(note ReaR's messages e.g. what log file it uses and so on).

In general regarding issues with Relax-and-Recover
have a look in particular at the sections
"Debugging issues with Relax-and-Recover"
and
"How to contribute to Relax-and-Recover"
in
https://en.opensuse.org/SDB:Disaster_Recovery