XDCR reports negative replication_changes_left values during initial replication

00:27:19.087 [17/Feb/2017 10:21:12] INFO - replication_changes_left = 15,960,504

00:27:21.105 [17/Feb/2017 10:21:14] INFO - replication_changes_left = 15,726,017

00:27:23.119 [17/Feb/2017 10:21:16] INFO - replication_changes_left = 15,501,673

00:27:25.134 [17/Feb/2017 10:21:18] INFO - replication_changes_left = 15,277,711

00:27:27.148 [17/Feb/2017 10:21:20] INFO - replication_changes_left = 14,929,779

00:27:29.161 [17/Feb/2017 10:21:22] INFO - replication_changes_left = 14,815,393

00:27:31.179 [17/Feb/2017 10:21:24] INFO - replication_changes_left = 14,593,009

00:27:33.194 [17/Feb/2017 10:21:26] INFO - replication_changes_left = 14,243,643

00:27:35.211 [17/Feb/2017 10:21:28] INFO - replication_changes_left = 14,011,477

00:27:37.229 [17/Feb/2017 10:21:30] INFO - replication_changes_left = 13,892,936

00:27:39.247 [17/Feb/2017 10:21:32] INFO - replication_changes_left = -1

00:27:41.266 [17/Feb/2017 10:21:34] INFO - replication_changes_left = -1

00:27:43.280 [17/Feb/2017 10:21:36] INFO - replication_changes_left = -86,790,346

00:27:45.301 [17/Feb/2017 10:21:38] INFO - replication_changes_left = 12,982,829

00:27:47.316 [17/Feb/2017 10:21:40] INFO - replication_changes_left = 12,759,704

00:27:49.331 [17/Feb/2017 10:21:42] INFO - replication_changes_left = 12,416,083

00:27:51.349 [17/Feb/2017 10:21:44] INFO - replication_changes_left = 12,301,086