Terminate subprocesses right way on cronstop

gluon/newcron.py

@@ -260,7 +260,10 @@ class cronlauncher(threading.Thread):
                                 shell=self.shell)
         _cron_subprocs.append(proc)
         (stdoutdata, stderrdata) = proc.communicate()
-        _cron_subprocs.remove(proc)
+        try:
+            _cron_subprocs.remove(proc)
+        except ValueError:
+            pass
         if proc.returncode != 0:
             logger.warning(
                 'WEB2PY CRON Call returned code %s:\n%s' %