partitioning: Handle exceptions differently for getDevice() and Disk()

This commit fixes a really bad bug.

If parted.getDevice() throws an exception:

- There's no need to format the device, we're dealing with something
which can't be read at device level here, not at partition table or
partition level.
- The disk_device variable is either NULL or worse, it still has
the value of the previous device. If the user answers YES to format the
device, it formats the previous one.

This bug is introduced by ad29db2 and
present in the LMDE 6 BETA.

usr/lib/live-installer/partitioning.py

@@ -102,10 +102,6 @@ def get_disks():
             if re.match("/dev/mmcblk[0-9]+rpmb$", device):
                 print("Excluding %s (eMMC hardware device)" % device)
                 continue
-            # Exclude empty devices (for instance: a card reader with no card in it)
-            if size[:-1] == "0":
-                print("Excluding %s (device's size is 0)" % device)
-                continue
 
             # Convert size to manufacturer's size (i.e. GB, not GiB)
             unit_index = 'BKMGTPEZY'.index(size.upper()[-1])
@@ -266,10 +262,16 @@ def __init__(self):
         print('Disks: ', self.disks)
         already_done_full_disk_format = False
         for disk_path, disk_description in self.disks:
+            # Get the device from parted
             try:
                 print("    Analyzing path='%s' description='%s'" % (disk_path, disk_description))
                 disk_device = parted.getDevice(disk_path)
                 print("      - Found the device...")
+            except Exception as detail:
+                print("      - Found an issue while looking for the device: %s" % detail)
+                continue
+            # Get the partitions from parted
+            try:
                 disk = parted.Disk(disk_device)
                 print("      - Found the disk...")
             except Exception as detail: