min-replicas-to-write: only deny write commands.

I guess I needed another coffee...

src/redis.c

@@ -1810,7 +1810,9 @@ int processCommand(redisClient *c) {
 
     /* Don't accept write commands if there are not enough good slaves and
      * used configured the min-slaves-to-write option. */
-    if (server.repl_min_slaves_to_write && server.repl_min_slaves_max_lag &&
+    if (server.repl_min_slaves_to_write &&
+        server.repl_min_slaves_max_lag &&
+        c->cmd->flags & REDIS_CMD_WRITE &&
         server.repl_good_slaves_count < server.repl_min_slaves_to_write)
     {
         flagTransaction(c);