Add Truncate flag so Dgraph won't fail to init on Windows.

dgraph/cmd/zero/run.go

@@ -168,6 +168,7 @@ func run() {
 	x.Checkf(os.MkdirAll(opts.w, 0700), "Error while creating WAL dir.")
 	kvOpt := badger.LSMOnlyOptions
 	kvOpt.SyncWrites = true
+	kvOpt.Truncate = true
 	kvOpt.Dir = opts.w
 	kvOpt.ValueDir = opts.w
 	kv, err := badger.Open(kvOpt)

edgraph/server.go

@@ -101,6 +101,7 @@ func (s *ServerState) initStorage() {
 	x.Checkf(os.MkdirAll(Config.WALDir, 0700), "Error while creating WAL dir.")
 	kvOpt := badger.LSMOnlyOptions
 	kvOpt.SyncWrites = true
+	kvOpt.Truncate = true
 	kvOpt.Dir = Config.WALDir
 	kvOpt.ValueDir = Config.WALDir
 	kvOpt.TableLoadingMode = options.MemoryMap
@@ -124,6 +125,7 @@ func (s *ServerState) initStorage() {
 		x.Fatalf("Invalid Badger options")
 	}
 	opt.SyncWrites = true
+	opt.Truncate = true
 	opt.Dir = Config.PostingDir
 	opt.ValueDir = Config.PostingDir
 	opt.NumVersionsToKeep = math.MaxInt32