Comment 1 for bug 1882873

I tried this with ml2/OVN on master and it seems to be working:

vagrant@devstack:~
$ openstack subnet set --gateway none subnetbug
[14:30:28]
vagrant@devstack:~
$ openstack subnet show subnetbug
+----------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Field | Value |
+----------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------+
| allocation_pools | 29::1-29::ffff:ffff:ffff:ffff |
| cidr | 29::/64 |
| created_at | 2020-06-10T14:29:06Z |
| description | |
| dns_nameservers | |
| dns_publish_fixed_ip | False |
| enable_dhcp | True |
| gateway_ip | None |
| host_routes | |
| id | 330cc9ce-7bdd-4b3c-8508-27c376dae666 |
| ip_version | 6 |
| ipv6_address_mode | None |
| ipv6_ra_mode | None |
| location | cloud='', project.domain_id='default', project.domain_name=, project.id='1e198452c7ed473bb565873f29811669', project.name='demo', region_name='RegionOne', zone= |
| name | subnetbug |
| network_id | 964b4cc3-de3b-4602-b209-75632d471972 |
| prefix_length | None |
| project_id | 1e198452c7ed473bb565873f29811669 |
| revision_number | 1 |
| segment_id | None |
| service_types | |
| subnetpool_id | None |
| tags | |
| updated_at | 2020-06-10T14:30:28Z |
+----------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------+

Can you please attach neutron server logs and the exact command that failed for you?