ifupdownmain: handle more than one upperifaces

Ticket: CM-9595
Reviewed By:
Testing Done: tested with failing vrf config in CM-9595

due to same upperiface getting processed more than once,
there was an unnecessary refcount inc on the lowerdevice.
This patch aborts processing upperiface if already
processed and also adds a new debug function to
dump lower and uppper ifaces of all interfaces in the
file.

ifupdown/iface.py

@@ -595,6 +595,12 @@ class iface():
         else:
             logger.info(indent + 'lowerdevs: None')
 
+        d = self.upperifaces
+        if d:
+            logger.info(indent + 'upperdevs: %s' %str(d))
+        else:
+            logger.info(indent + 'upperdevs: None')
+
         logger.info(indent + 'config: ')
         config = self.config
         if config: