protect against changes to Python interface layer

direct/src/showbase/PythonUtil.py

@@ -2456,7 +2456,8 @@ def _getDtoolSuperBase():
     global dtoolSuperBase
     from pandac.PandaModules import PandaNode
     dtoolSuperBase = PandaNode('').__class__.__bases__[0].__bases__[0].__bases__[0]
-
+    assert repr(dtoolSuperBase) == "<type 'libdtoolconfig.DTOOL_SUPPER_BASE111'>"
+    
 safeReprNotify = None
 
 def _getSafeReprNotify():