Fix memory corruption bug in impl/memory

impl/memory/datastore.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package memory
 
 import (
         "errors"
         "fmt"
 
@@ skipping 120 matching lines @@
         }
 
         d.data.addIndexes(idxs)
 }
 
 func (d *dsImpl) TakeIndexSnapshot() ds.TestingSnapshot {
         return d.data.takeSnapshot()
 }
 
 func (d *dsImpl) SetIndexSnapshot(snap ds.TestingSnapshot) {
-        d.data.setSnapshot(snap.(*memStore))
+        d.data.setSnapshot(snap.(memStore))
 }
 
 func (d *dsImpl) CatchupIndexes() {
         d.data.catchupIndexes()
 }
 
 func (d *dsImpl) SetTransactionRetryCount(count int) {
         d.data.setTxnRetry(count)
 }
 
@@ skipping 66 matching lines @@
         return countQuery(fq, d.data.parent.aid, d.ns, true, d.data.snap, d.data.snap)
 }
 
 func (*txnDsImpl) RunInTransaction(func(c context.Context) error, *ds.TransactionOptions) error {
         return errors.New("datastore: nested transactions are not supported")
 }
 
 func (*txnDsImpl) Testable() ds.Testable {
         return nil
 }