pop() does check existence of key

src/ZODB/Connection.py

@@ -762,8 +762,7 @@ class Connection(ExportImport, object):
             self._creating = {}
 
         for oid in creating:
-            if oid in self._readCurrent:
-                self._readCurrent.pop(oid, None)
+            self._readCurrent.pop(oid, None)
             o = self._cache.get(oid)
             if o is not None:
                 del self._cache[oid]