Due to timing issues, when the agent synchronizes
with the server wrt the representation of server's
and agent's networks, networks may have already
been deleted from the db. In such circumstances,
it is more appropriate to emit warnings rather than
full-blown exceptions as the agent handles these
circumstances just fine.
Close-bug: 1251874
Change-Id: I4b118b6087c7f42226f0d4265d2176c028d99f22