When user sets snapshot thick origin as read-only - lvconvert --merge refuses
to merge until user swiches origin to 'read-write'.
# make sure lvconvert --merge requires explicit LV listing
not lvconvert --merge
+# check read-only origin is protected from being merge
+lvchange -pr $vg/$lv1
+not lvconvert --merge "$vg/$(snap_lv_name_ "$lv1")" |& tee out
+grep "read-only origin" out
+lvchange -prw $vg/$lv1
+
# check exclusive lock is preserved after merge
check lv_field "$vg/$lv1" lv_active_exclusively "active exclusively"
lvconvert --merge "$vg/$(snap_lv_name_ "$lv1")"