python: ovsdb-idl: Handle inserts w/o changes.

If a table's schema allows no columns to be set when inserting,
python-ovs should handle that case.

Signed-off-by: Terry Wilson <twilson@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

python/ovs/db/idl.py

@@ -1856,7 +1856,7 @@ class Transaction(object):
                 else:
                     # Let ovsdb-server decide whether to really delete it.
                     pass
-            elif row._changes:
+            else:
                 op = {"table": row._table.name}
                 if row._data is None:
                     op["op"] = "insert"