zzlIsInRange() now is capable of handling empty sorted sets that may …

…end inside the data set when loading very old RDB files produced by early-stage versions of Redis.

src/t_zset.c

@@ -504,7 +504,7 @@ int zzlIsInRange(unsigned char *zl, zrangespec *range) {
         return 0;
 
     p = ziplistIndex(zl,-1); /* Last score. */
-    redisAssert(p != NULL);
+    if (p == NULL) return 0; /* Empty sorted set */
     score = zzlGetScore(p);
     if (!zslValueGteMin(score,range))
         return 0;