DB.open() doesn't support the `mvcc` parameter in ZODB 3.8, so...

DB.open() doesn't support the `mvcc` parameter in ZODB 3.8, so `checkWithoutMVCCRaisesReadConflict` won't raise a `ReadConflictError` either

lib/python/tempstorage/tests/testTemporaryStorage.py

@@ -56,7 +56,7 @@ class TemporaryStorageTests(
 
     def doreadconflict(self, db, mvcc):
         tm1 = transaction.TransactionManager()
-        conn = db.open(mvcc=mvcc, transaction_manager=tm1)
+        conn = db.open(transaction_manager=tm1)
         r1 = conn.root()
         obj = MinPO('root')
         r1["p"] = obj
@@ -66,7 +66,7 @@ class TemporaryStorageTests(
 
         # start a new transaction with a new connection
         tm2 = transaction.TransactionManager()
-        cn2 = db.open(mvcc=mvcc, transaction_manager=tm2)
+        cn2 = db.open(transaction_manager=tm2)
         r2 = cn2.root()
 
         self.assertEqual(r1._p_serial, r2._p_serial)
@@ -85,10 +85,6 @@ class TemporaryStorageTests(
         obj.child1 
         return obj
 
-    def checkWithoutMVCCRaisesReadConflict(self):
-        db = DB(self._storage)
-        self.assertRaises(ReadConflictError, self.doreadconflict, db, False)
-
     def checkWithMVCCDoesntRaiseReadConflict(self):
         db = DB(self._storage)
         ob = self.doreadconflict(db, True)