ifupdown: iface: if auto %ifacename is not part of the first stanza we squash it

Ticket: CM-12713
Reviewed By: Roopa, Nikhil G
Testing Done: Test from the bug

% for i in range(1,49):
iface swp${i}
    mtu 9216
    link-speed 10000
    link-duplex full
    link-autoneg off
% endfor

auto swp1
iface swp1

% ifup -a -v # should only up swp1

Signed-off-by: Julien Fortin <julien@cumulusnetworks.com>

ifupdown/iface.py

@@ -585,6 +585,10 @@ class iface():
                 self.config.update([(attrname, attrlist)])
         # we now support inet and inet6 together
         self.addr_family.extend(newifaceobj.addr_family)
+        # if auto %ifacename is not part of the first stanza
+        # we need to squash it
+        if not self.auto and newifaceobj.auto:
+            self.auto = True
 
     def __getstate__(self):
         odict = self.__dict__.copy()