Sentinel: fix reported role info sampling.

The way the role change was recoded was not sane and too much
convoluted, causing the role information to be not always updated.

This commit fixes issue #1445.

src/sentinel.c

@@ -1764,22 +1764,22 @@ void sentinelRefreshInstanceInfo(sentinelRedisInstance *ri, const char *info) {
      * Some things will not happen if sentinel.tilt is true, but some will
      * still be processed. */
 
-    /* Handle master -> slave role switch. */
-    if ((ri->flags & SRI_MASTER) && role == SRI_SLAVE) {
-        if (ri->role_reported != SRI_SLAVE) {
+    /* Remember when the role changed. */
+    if (role != ri->role_reported) {
         ri->role_reported_time = mstime();
-            ri->role_reported = SRI_SLAVE;
-            ri->slave_conf_change_time = mstime();
+        ri->role_reported = role;
+        if (role == SRI_SLAVE) ri->slave_conf_change_time = mstime();
     }
+
+    /* Handle master -> slave role switch. */
+    if ((ri->flags & SRI_MASTER) && role == SRI_SLAVE) {
+        /* Nothing to do, but masters claiming to be slaves are
+         * considered to be unreachable by Sentinel, so eventually
+         * a failover will be triggered. */
     }
 
     /* Handle slave -> master role switch. */
     if ((ri->flags & SRI_SLAVE) && role == SRI_MASTER) {
-        if (ri->role_reported != SRI_MASTER) {
-            ri->role_reported_time = mstime();
-            ri->role_reported = SRI_MASTER;
-        }
-
         /* If this is a promoted slave we can change state to the
          * failover state machine. */
         if (!sentinel.tilt &&