Investigate possible bug related to replication lag

[renecannao]

Investigate this output:

mysql> select hostgroup,srv_host,status from stats.stats_mysql_connection_pool;
+-----------+--------------+-------------------------+
| hostgroup | srv_host     | status                  |
+-----------+--------------+-------------------------+
| 1         | 172.30.4.169 | SHUNNED_REPLICATION_LAG |
| 1         | 172.30.4.171 | SHUNNED_REPLICATION_LAG |
| 1         | 172.30.4.169 | ONLINE                  |
| 1         | 172.30.4.171 | ONLINE                  |
| 0         | 172.30.4.36  | ONLINE                  |
+-----------+--------------+-------------------------+

[krzysztof-ksiazek]

1. UPDATE mysql_servers SET max_replication_lag=5; LOAD MYSQL SERVERS TO RUNTIME;
2. Induce lag so nodes will be shunned
3. while nodes are shunned, UPDATE mysql_servers SET max_replication_lag=0; LOAD MYSQL SERVERS TO RUNTIME;

This also seems to impact proxy's ability to lag-shun slaves which happened to be duplicated.