Differentiate between single- and multi- props.

impl/memory/datastore_data.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package memory
 
 import (
         "bytes"
         "fmt"
         "strings"
@@ skipping 175 matching lines @@
 func rootIDsKey(kind string) []byte {
         return keyBytes(ds.NewKey("", "", "__entity_root_ids__", kind, 0, nil))
 }
 
 func curVersion(ents memCollection, key []byte) int64 {
         if ents != nil {
                 if v := ents.Get(key); v != nil {
                         pm, err := rpm(v)
                         memoryCorruption(err)
 
-                        pl, ok := pm["__version__"]
-                        if ok && len(pl) > 0 && pl[0].Type() == ds.PTInt {
+                        pl := pm.Slice("__version__")
+                        if len(pl) > 0 && pl[0].Type() == ds.PTInt {
                                 return pl[0].Value().(int64)
                         }
 
                         memoryCorruption(fmt.Errorf("__version__ property missing or wrong: %v", pm))
                 }
         }
         return 0
 }
 
 func incrementLocked(ents memCollection, key []byte, amt int) int64 {
         if amt <= 0 {
                 panic(fmt.Errorf("incrementLocked called with bad `amt`: %d", amt))
         }
         ret := curVersion(ents, key) + 1
         ents.Set(key, serialize.ToBytes(ds.PropertyMap{
-                "__version__": {ds.MkPropertyNI(ret + int64(amt-1))},
+                "__version__": ds.MkPropertyNI(ret + int64(amt-1)),
         }))
         return ret
 }
 
 func (d *dataStoreData) allocateIDs(keys []*ds.Key, cb ds.NewKeyCB) error {
         // Map keys by entity type.
         entityMap := make(map[string][]int)
         for i, key := range keys {
                 ks := key.String()
                 entityMap[ks] = append(entityMap[ks], i)
@@ skipping 396 matching lines @@
         }
         return namespaces
 }
 
 func trimPrefix(v, p string) (string, bool) {
         if strings.HasPrefix(v, p) {
                 return v[len(p):], true
         }
         return v, false
 }