Change test for None oid in invalidate() to assert.

Reindent MUCH_RING_CHECKING test.

src/ZODB/Connection.py

@@ -13,7 +13,7 @@
 ##############################################################################
 """Database connection support
 
-$Id: Connection.py,v 1.68 2002/06/12 15:30:05 jeremy Exp $"""
+$Id: Connection.py,v 1.69 2002/06/12 19:40:47 jeremy Exp $"""
 
 from cPickleCache import PickleCache, MUCH_RING_CHECKING
 from POSException import ConflictError, ReadConflictError
@@ -225,7 +225,7 @@ class Connection(ExportImport.ExportImport):
         if object is self:
             self._cache.invalidate(self._invalidated)
         else:
-            if object._p_oid is not None:
+            assert object._p_oid is not None
             self._cache.invalidate(object._p_oid)
 
     def cacheFullSweep(self, dt=0):