Bugfix: Only try to compare stratum job_id for work that has a job_id (ie, ones that came from stratum)

cgminer.c

@@ -3185,7 +3185,7 @@ static bool stale_work(struct work *work, bool share)
 
 	pool = work->pool;
 
-	if (pool->has_stratum) {
+	if (pool->has_stratum && work->job_id) {
 		bool same_job = true;
 
 		mutex_lock(&pool->pool_lock);