Fix ZINCRBY return value.

src/t_zset.c

@@ -1308,6 +1308,7 @@ int zsetAdd(robj *zobj, double score, sds ele, int *flags, double *newscore) {
                 zsetConvert(zobj,OBJ_ENCODING_SKIPLIST);
             if (sdslen(ele) > server.zset_max_ziplist_value)
                 zsetConvert(zobj,OBJ_ENCODING_SKIPLIST);
+            if (newscore) *newscore = score;
             *flags |= ZADD_ADDED;
             return 1;
         } else {
@@ -1359,6 +1360,7 @@ int zsetAdd(robj *zobj, double score, sds ele, int *flags, double *newscore) {
             znode = zslInsert(zs->zsl,score,ele);
             serverAssert(dictAdd(zs->dict,ele,&znode->score) == DICT_OK);
             *flags |= ZADD_ADDED;
+            if (newscore) *newscore = score;
             return 1;
         } else {
             *flags |= ZADD_NOP;

tests/unit/type/zset.tcl

@@ -290,6 +290,12 @@ start_server {tags {"zset"}} {
             assert_equal  6 [r zscore zset bar]
         }
 
+        test "ZINCRBY return value" {
+            r del ztmp
+            set retval [r zincrby ztmp 1.0 x]
+            assert {$retval == 1.0}
+        }
+
         proc create_default_zset {} {
             create_zset zset {-inf a 1 b 2 c 3 d 4 e 5 f +inf g}
         }