min-slaves-to-write: don't accept writes with less than N replicas.

This feature allows the user to specify the minimum number of
connected replicas having a lag less or equal than the specified
amount of seconds for writes to be accepted.

src/networking.c

@@ -692,6 +692,7 @@ void freeClient(redisClient *c) {
          * backlog. */
         if (c->flags & REDIS_SLAVE && listLength(server.slaves) == 0)
             server.repl_no_slaves_since = server.unixtime;
+        refreshGoodSlavesCount();
     }
 
     /* Case 2: we lost the connection with the master. */