fix gc

de.churl.simple/garbagecollection.py

@@ -1,12 +1,14 @@
 def mark(w_context):
+    if w_context.mark:  # skip cycles
+        return
+
     w_context.mark = True
 
     if not hasattr(w_context, "slots"):  # skip primitive objects
         return
 
     for name, obj in w_context.slots.items():
-        if name != "__parent__":  # only descent
-            mark(obj)
+        mark(obj)
 
 
 def sweep(objects):

de.churl.simple/objspace.py

@@ -44,7 +44,8 @@ class ObjectSpace(object):
         else:
             slots = {'__parent__': self.getbuiltins()}
 
-        return W_NormalObject(name=name, slots=slots)  # lobby isn't collected
+        self.objects.append(W_NormalObject(name=name, slots=slots))  # needed, otherwise marking skips the root
+        return self.objects[-1]
 
     def newobject(self, name, slots, parentnames):
         self.objects.append(W_NormalObject(space=self, name=name,