Redis zrangebyscore returns nil instead of (empty array) with RESP2

Forwarding of KeyDB bug: https://github.com/JohnSully/KeyDB/issues/61

Repro:

   #build a largish sorted set that will be skiplist encoded
   $ redis-cli zadd foo 5 `seq 0 1000`
   (integer) 501
   $ redis-cli debug object foo
   Value at:0x7f830fa5ee48 refcount:1 encoding:skiplist serializedlength:5449 lru:3126995 lru_seconds_idle:8
   $ redis-cli zrangebyscore foo -inf -1
   (nil)

Expected: (empty array)

This is a regression from RESP3 work. It is expected to return (nil) only for RESP3 clients.

See here for this fix: https://github.com/JohnSully/KeyDB/commit/4e30a5b4e53a4d1580f8d7cca8a8eac11e36ce4d

Comment From: enjoy-binbin

Looks like it's been fixed, can you confirm again? (i can not find the fix commit, there are too much change in blame log)

# unsable branch, skiplist, RESP2 or 3
127.0.0.1:6379> zadd foo 5 `seq 0 1000`
(integer) 2
127.0.0.1:6379> zrangebyscore foo -inf -1
(empty array)
127.0.0.1:6379> zrangebyscore foo 0 -1
(empty array)
127.0.0.1:6379> zrangebyscore foo 0 10000
1) "1000`"
2) "`seq"