storage/lvm: fix listing volume revisions when VM name include volume name

some-vm-root is a valid VM name, and in that case it's volume can be
named some-vm-root-private. Do not let it confuse revision listing,
check for unexpected '-' in volume revision number.

The proper solution would be to use different separator, that is not
allowed in VM names. But that would require migration code that is
undesired in the middle of stable release life cycle.

Fixes QubesOS/qubes-issues#4680

qubes/storage/lvm.py

@@ -327,6 +327,9 @@ class ThinVolume(qubes.storage.Volume):
             if not revision_vid.endswith('-back'):
                 continue
             revision_vid = revision_vid[len(name_prefix):]
+            if revision_vid.count('-') > 1:
+                # VM+volume name is a prefix of another VM, see #4680
+                continue
             # get revision without suffix
             seconds = int(revision_vid.split('-')[0])
             iso_date = qubes.storage.isodate(seconds).split('.', 1)[0]