Reset shardjedis datasource (#1939)

Reset shardjedis dataSource before returned to pool

Related to #1920
As it had fixed in Jedis.java, SharedJedis.java should be fixed too.

Author: timothyzhw

src/main/java/redis/clients/jedis/ShardedJedis.java

@@ -822,13 +822,13 @@ public void close() {
           break;
         }
       }
-
+      ShardedJedisPool pool = this.dataSource;
+      this.dataSource = null;
       if (broken) {
-        dataSource.returnBrokenResource(this);
+        pool.returnBrokenResource(this);
       } else {
-        dataSource.returnResource(this);
+        pool.returnResource(this);
       }
-      this.dataSource = null;
 
     } else {
       disconnect();