fix volume placement validating

fix https://github.com/chrislusf/seaweedfs/issues/1626

weed/shell/command_volume_balance_test.go

@@ -20,6 +20,22 @@ func TestIsGoodMove(t *testing.T) {
 
 	var tests = []testMoveCase{
 
+		{
+			name:        "test 100 move to wrong data centers",
+			replication: "100",
+			replicas: []*VolumeReplica{
+				{
+					location: &location{"dc1", "r1", &master_pb.DataNodeInfo{Id: "dn1"}},
+				},
+				{
+					location: &location{"dc2", "r2", &master_pb.DataNodeInfo{Id: "dn2"}},
+				},
+			},
+			sourceLocation: location{"dc1", "r1", &master_pb.DataNodeInfo{Id: "dn1"}},
+			targetLocation: location{"dc2", "r3", &master_pb.DataNodeInfo{Id: "dn3"}},
+			expected:       false,
+		},
+
 		{
 			name:        "test 100 move to spread into proper data centers",
 			replication: "100",