Force use of the new TimerServer

By importing the new TimerService unconditionally,
the commit 34c81caf
(Timeout: introduce publisher_timeout configuration)
broke automatic site creation & publisher timeout
when the zope config specifies the old timerserver.

product/ERP5/ERP5Site.py

@@ -2485,16 +2485,7 @@ def initialize(self):
               'MySQL error while trying to create ERP5 site. Retrying...',
               error=1)
         time.sleep(5)
-  try:
-    TimerServer = sys.modules['Products.TimerService.timerserver.TimerServer']
-  except KeyError:
-    try: # BBB
-      TimerServer = sys.modules['timerserver.TimerServer']
-    except KeyError:
-      # There's no point installing ERP5 automatically
-      # if there's no timer service configured.
-      return
-  TimerRequest = TimerServer.TimerRequest
+  from Products.TimerService.timerserver.TimerServer import TimerRequest
   def traverse(*args, **kw):
     del TimerRequest.traverse
     return addERP5Site

product/TimerService/__init__.py

@@ -2,6 +2,7 @@
 # -*- Mode: Python; py-indent-offset: 4 -*-
 # Authors: Nik Kim <fafhrd@legco.biz>
 
+import sys
 from App.ImageFile import ImageFile
 from .TimerService import TimerService, current_version
 
@@ -25,3 +26,13 @@ def getTimerService(context):
             control_panel._delObject(cp_id)
         root._setObject(cp_id, timer_service)
     return timer_service
+
+try:
+    old = sys.modules['timerserver']
+except KeyError:
+    pass
+else: # BBB: old timerserver loaded from zope config, force use of new one
+    assert 'timerserver.TimerServer' not in sys.modules
+    from .timerserver import TimerServerFactory
+    old.TimerServerFactory.create = TimerServerFactory.create.__func__
+    del old, TimerServerFactory