Force adding TCONT to internal DB irrespective of it was added before or not.

Change-Id: Id23fcdcdad6918e92133223ac40eb4dee29d49fe
diff --git a/python/adapters/brcm_openomci_onu/pon_port.py b/python/adapters/brcm_openomci_onu/pon_port.py
index 634fd7e..2ee3344 100644
--- a/python/adapters/brcm_openomci_onu/pon_port.py
+++ b/python/adapters/brcm_openomci_onu/pon_port.py
@@ -177,7 +177,8 @@
             return False # already created
 
         self.log.info('add-tcont', tcont=tcont.alloc_id, reflow=reflow)
-        self._tconts[tcont.alloc_id] = tcont
+        if tcont.alloc_id not in self._tconts:
+            self._tconts[tcont.alloc_id] = tcont
         return True
 
     @inlineCallbacks