Description of problem:

When plugging in a USB multi-card reader (SD / MicroSD) which has no card insert, the device (/dev/sda) has a 0 size.
This leads to layout verification to fail:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
No partition label type for 'disk /dev/sda' (may cause 'rear recover' failure)
/dev/sda size 0 is not a positive integer
ERROR: 
====================
BUG in /root/rear/usr/share/rear/layout/save/default/950_verify_disklayout_file.sh line 254:
'Entries in /root/rear/var/lib/rear/layout/disklayout.conf are broken ('rear recover' would fail)'
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

This happens when AUTOEXCLUDE_DISKS=n (which is not the default).

The root cause is the code snippet in /usr/share/rear/layout/save/GNU/Linux/200_partition_layout.sh, which doesn't skip disks with $devsize == 0 :
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
415                 devsize=$(get_disk_size ${disk#/sys/block/})
416                 disktype=$(parted -s $devname print | grep -E "Partition Table|Disk label" | cut -d ":" -f "2" | t    r -d " ")
 :
430                     echo "disk $devname $devsize $disktype"
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

This leads to creating entry disk sda 0, which is invalid entry (missing $disktype).

I think the solution is to skip those 0 size disks completely.

Version-Release number of selected component (if applicable):

rear-2.6+

How reproducible:

Always, see above.