Sentinel: more easy master redirection if master is a slave.

Before this commit Sentienl used to redirect master ip/addr if the
current instance reported to be a slave only if this was the first INFO
output received, and the role was found to be slave.

Now instead also if we find that the runid is different, and the
reported role is slave, we also redirect to the reported master ip/addr.

This unifies the behavior of Sentinel in the case of a reboot (where it
will see the first INFO output with the wrong role and will perform the
redirection), with the behavior of Sentinel in the case of a change in
what it sees in the INFO output of the master.

src/sentinel.c

@@ -1426,7 +1426,7 @@ void sentinelRefreshInstanceInfo(sentinelRedisInstance *ri, const char *info) {
 
     /* Act if a master turned into a slave. */
     if ((ri->flags & SRI_MASTER) && role == SRI_SLAVE) {
-        if (first_runid && ri->slave_master_host) {
+        if ((first_runid || runid_changed) && ri->slave_master_host) {
             /* If it is the first time we receive INFO from it, but it's
              * a slave while it was configured as a master, we want to monitor
              * its master instead. */
@@ -1445,7 +1445,7 @@ void sentinelRefreshInstanceInfo(sentinelRedisInstance *ri, const char *info) {
         if (!(ri->master->flags & SRI_FAILOVER_IN_PROGRESS) &&
             (runid_changed || first_runid))
         {
-            /* If a slave turned into maser but:
+            /* If a slave turned into master but:
              *
              * 1) Failover not in progress.
              * 2) RunID hs changed, or its the first time we see an INFO output.