Delete db error when syncing vlan allocation

[sunzuohua]

Reproduction steps:
1.Remove existed physical network in network_vlan_ranges from ml2_conf.ini
2.Restart neutron server
3.Fail to restart neutron server and report error as follows:
    UnmappedInstanceError: Class 'neutron.objects.plugins.ml2.vlanallocation.VlanAllocation' is not mapped

Solution:
Modify [1] as follows:
    alloc.delete()

[1]https://github.com/openstack/neutron/blob/master/neutron/plugins/ml2/drivers/type_vlan.py#L133

[Deepak Mourya (mourya007)]

i could not reproduced the same error on my environment

[sunzuohua (zuohuasun)]

@Deepak Mouryam, You have to remove the entire physical network segment, just the vlan range.