diff -r d9175daf6522 -r 985973ed701b runtime/Worker.py
--- a/runtime/Worker.py	Tue Aug 21 16:11:02 2018 +0200
+++ b/runtime/Worker.py	Wed Sep 05 12:58:41 2018 +0200
@@ -76,7 +76,7 @@
 
         _job = job(*args, **kwargs)
 
-        if self._threadID == thread.get_ident() or self._threadID is None:
+        if self._threadID == thread.get_ident():
             # if caller is worker thread execute immediately
             _job.do()
         else: