worker test: do not close the event loop twice

artiq/test/worker.py

@@ -40,7 +40,6 @@ def _call_worker(worker, expid):
 
 
 def _run_experiment(experiment):
-    try:
     expid = {
         "file": sys.modules[__name__].__file__,
         "experiment": experiment,
@@ -53,8 +52,6 @@ def _run_experiment(experiment):
     loop = asyncio.get_event_loop()
     worker = Worker(handlers)
     loop.run_until_complete(_call_worker(worker, expid))
-    finally:
-        loop.close()
 
 
 class WatchdogCase(unittest.TestCase):