--slave-info with multi-master replication shows "m"s MySQL slave binlog position

[Shahriyar Rzayev]

Testing:
https://bugs.launchpad.net/percona-xtrabackup/+bug/1551634

With multi-master replication I took a backup from one of the nodes as:

xtrabackup --defaults-file=/home/shahriyar.rzaev/sandboxes/multi_msb_5_7_18/node4/my.sandbox.cnf --user=msandbox --password='msandbox' --target-dir=/home/shahriyar.rzaev/backup_dir/ps_5.7_multi_source_repl/full/2017-07-20_13-10-31 --backup --host=127.0.0.1 --port=14522 --binlog-info=AUTO --galera-info --parallel 4 --check-privileges --no-version-check --slave-info

170720 13:10:44 Backup created in directory '/home/shahriyar.rzaev/backup_dir/ps_5.7_multi_source_repl/full/2017-07-20_13-10-31/'
MySQL binlog position: filename 'mysql-bin.000004', position '154', GTID of the last change '00014519-1111-1111-1111-111111111111:1-17,
00014520-2222-2222-2222-222222222222:1-5,
00014521-3333-3333-3333-333333333333:1-12'
MySQL slave binlog position:
m
m
m
170720 13:10:44 [00] Writing /home/shahriyar.rzaev/backup_dir/ps_5.7_multi_source_repl/full/2017-07-20_13-10-31/backup-my.cnf
170720 13:10:44 [00] ...done
170720 13:10:44 [00] Writing /home/shahriyar.rzaev/backup_dir/ps_5.7_multi_source_repl/full/2017-07-20_13-10-31/xtrabackup_info
170720 13:10:44 [00] ...done
xtrabackup: Transaction log of lsn (2639746) to (2643180) was copied.
170720 13:10:44 completed OK!

As you see the "m"s showed up in the output.