tests: drop references to qubes objects via lists too

There is a code that drops references to Qubes* objects saved directly
in test instance attributes already. But 274bb39 "Set deferred netvm
for paused clients on shutdown" introduced also a list of such objects,
which weren't cleaned up. Fix it by considering lists too - if first
element is a qubes object, remove the whole list.

Fixes: 274bb39 "Set deferred netvm for paused clients on shutdown"

Author: marmarek

qubes/tests/__init__.py

@@ -931,6 +931,12 @@ def cleanup_app(self):
             obj_type = type(getattr(self, attr))
             if obj_type.__module__.startswith("qubes"):
                 delattr(self, attr)
+            elif issubclass(obj_type, list) and any(
+                type(obj).__module__.starswith("qubes")
+                for obj in getattr(self, attr)
+            ):
+                # remove also list of qubes objects
+                delattr(self, attr)
 
         # then trigger garbage collector to really destroy those objects
         gc.collect()