shell: volume.tier.move avoid moving all volumes to one destination

weed/shell/command_volume_fix_replication.go

@@ -195,6 +195,8 @@ func (c *commandVolumeFixReplication) fixOneUnderReplicatedVolume(commandEnv *Co
 			fmt.Fprintf(writer, "replicating volume %d %s from %s to dataNode %s ...\n", replica.info.Id, replicaPlacement, replica.location.dataNode.Id, dst.dataNode.Id)
 
 			if !takeAction {
+				// adjust free volume count
+				dst.dataNode.DiskInfos[replica.info.DiskType].FreeVolumeCount--
 				break
 			}