rear mkrescue shows "Using backup archive" message

[gdha]

• rear version (/usr/sbin/rear -V): master git
• OS version (cat /etc/rear/os.conf or lsb_release -a): centos 7.3
• Brief description of the issue:
  I find it rather strange when running rear mkrescue that we see the following message:

# rear -vd mkrescue
Relax-and-Recover 2.00-git201705081501 / 2017-05-08
Using log file: /var/log/rear/rear-client.log
Using backup archive '/tmp/rear.B9uTEKRZLGjnpxn/outputfs/client/backup.tar.gz'
Creating disk layout

[jsmeix]

I know it since a long time.
It is because same stuff is run for "mkbackup" and "mkrescue".
I had a look but found no time to properly clean it up.
Things are too much interwoven for a quick and clean fix.

[jsmeix]

The root cause is that both WORKFLOW_mkbackup
and WORKFLOW_mkrescue need to run the 'prep' stage
and the 'prep' stage contains
prep/NETFS/default/070_set_backup_archive.sh

Or in other words:
Creating the backup is implemented intermixed
with creating the rescue/recovery system
but actually creating the backup happens
usually after creating the rescue/recovery system
except for WORKFLOW_mkbackup on USB where
things are additionally intermixed in another way.

[gdha]

@jsmeix Thanks Johannes for your review. I will try to fix this one later this month.

[jsmeix]

Nothing that needs to be done for ReaR 2.3
so that I set the milestone to ReaR 2.4

[gdha]

moving to 2.5

[gdha]

mkbackuponly-workflow.sh:    SourceStage "prep"
mkbackup-workflow.sh:	SourceStage "prep"
mkopalpba-workflow.sh:	SourceStage "prep"
mkrescue-workflow.sh:	SourceStage "prep"

are the workflows using the prep phase

[jsmeix]

This needs a more careful analysis whether or not
usr/share/rear/output/ISO/Linux-i386/810_prepare_multiple_iso.sh
still works o.k. when the variable backuparchive is no longer set in
usr/share/rear/prep/NETFS/default/070_set_backup_archive.sh
in case of the 'mkrescue' workflow.

See
#2063 (comment)

[jsmeix]

With
77cb3c2
and
4e03733
I added comments to
usr/share/rear/prep/NETFS/default/070_set_backup_archive.sh
and
usr/share/rear/output/ISO/Linux-i386/810_prepare_multiple_iso.sh
that describe the above described interdependency between
prep/NETFS/default/070_set_backup_archive.sh and
output/ISO/Linux-i386/810_prepare_multiple_iso.sh
that exists except for the mkrescue workflow.