Fix incorrect worker timeout calculation in SimpleWorker.execute_job (#1304)

In our systems, this bug seemed the be the cause of the disappearing workers: worker keys would get a very small TTL in Redis and would eventually expire, thus mysteriously "disappearing" from dashboards.

rq/worker.py

@@ -1034,6 +1034,10 @@ class SimpleWorker(Worker):
 
     def execute_job(self, job, queue):
         """Execute job in same thread/process, do not fork()"""
+        # "-1" means that jobs never timeout. In this case, we should _not_ do -1 + 60 = 59. We should just stick to DEFAULT_WORKER_TTL.
+        if job.timeout == -1:
+               timeout = DEFAULT_WORKER_TTL
+        else:
                timeout = (job.timeout or DEFAULT_WORKER_TTL) + 60
         return self.perform_job(job, queue, heartbeat_ttl=timeout)