Lagging replicas should not affect WaitSlaveCount

[teem0n]

If all replicas are lagging - mysync enables semi-sync on master and it will stuck in following way:

WARN: calc active nodes: replica_1 has data lag 92799618, but it's IO is working. Old binlog: mysql-bin-log-master.0027440000000000265253468, new binlog: mysql-bin-log-master.0027540000000000000000237
WARN: calc active nodes: replica_2 has data lag 92799851, but it's IO is working. Old binlog: mysql-bin-log-master.0027450000000000000005651, new binlog: mysql-bin-log-master.0027540000000000000000004
INFO: update active nodes: active nodes are: [master replica_1 replica_2], wait_slave_count 1
INFO: update active nodes: master change wait_slave_count: 0 => 1
DEBUG: node master running query 'SELECT 1 AS Ok' with args struct {}{}, result: &mysql.pingResult{Ok:1}, error: <nil>
DEBUG: node master running query 'SET GLOBAL rpl_semi_sync_master_enabled = 1, rpl_semi_sync_slave_enabled = 0' with args map[string]interface {}{}, result: <nil>, error: <nil>
DEBUG: node replica_1 running query 'SET GLOBAL rpl_semi_sync_slave_enabled = 0, rpl_semi_sync_master_enabled = 0' with args map[string]interface {}{}, result: <nil>, error: <nil>
DEBUG: node replica_2 running query 'SET GLOBAL rpl_semi_sync_slave_enabled = 0, rpl_semi_sync_master_enabled = 0' with args map[string]interface {}{}, result: <nil>, error: <nil>