Comment 2 for bug 1404809

> I guess this issue could be caused by this commit: https://github.com/stackforge/fuelweb/commit/5f91157daa6798ff522ca9f6d34e7e135f150a90

Nope, it was introduced a time ago. This commit just move 6.0-specific serialisation code to the specific serializer so the default_gateway won't be serialised for older releases.

As for this issue, we already have the fix - https://review.openstack.org/#/c/142136/