Fix sentinel issue if replica changes IP (#11590)

As Sentinel supports dynamic IP only when using hostnames, there
are few leftover addess comparison logic that doesn't take into
account that the IP might get change.

Co-authored-by: moticless <moticless@github.com>
(cherry picked from commit 4a27aa4875)

src/sentinel.c

@@ -640,11 +640,6 @@ void releaseSentinelAddr(sentinelAddr *sa) {
     zfree(sa);
 }
 
-/* Return non-zero if two addresses are equal. */
-int sentinelAddrIsEqual(sentinelAddr *a, sentinelAddr *b) {
-    return a->port == b->port && !strcasecmp(a->ip,b->ip);
-}
-
 /* Return non-zero if the two addresses are equal, either by address
  * or by hostname if they could not have been resolved.
  */
@@ -1664,7 +1659,7 @@ int sentinelResetMasterAndChangeAddress(sentinelRedisInstance *master, char *hos
     while((de = dictNext(di)) != NULL) {
         sentinelRedisInstance *slave = dictGetVal(de);
 
-        if (sentinelAddrIsEqual(slave->addr,newaddr)) continue;
+        if (sentinelAddrOrHostnameEqual(slave->addr,newaddr)) continue;
         slaves[numslaves++] = dupSentinelAddr(slave->addr);
     }
     dictReleaseIterator(di);
@@ -1672,7 +1667,7 @@ int sentinelResetMasterAndChangeAddress(sentinelRedisInstance *master, char *hos
     /* If we are switching to a different address, include the old address
      * as a slave as well, so that we'll be able to sense / reconfigure
      * the old master. */
-    if (!sentinelAddrIsEqual(newaddr,master->addr)) {
+    if (!sentinelAddrOrHostnameEqual(newaddr,master->addr)) {
         slaves[numslaves++] = dupSentinelAddr(master->addr);
     }
 
@@ -2221,7 +2216,7 @@ void rewriteConfigSentinelOption(struct rewriteConfigState *state) {
              * slave's address, a failover is in progress and the slave was
              * already successfully promoted. So as the address of this slave
              * we use the old master address instead. */
-            if (sentinelAddrIsEqual(slave_addr,master_addr))
+            if (sentinelAddrOrHostnameEqual(slave_addr,master_addr))
                 slave_addr = master->addr;
             line = sdscatprintf(sdsempty(),
                 "sentinel known-replica %s %s %d",