l2vpn rollback deletes endpoints object when VLAN assigment is not found

[usmanazFIU]

when trying to PATCH a l2vpn and changing VLAN from 3849 to 3850 in the following example. the sdx-controller rollbacks but in doing so deletes the endpoints.

endpoints object goes missing or deleted

[italovalcy]

The SDX-COntroller provides a very weird L2VPN when querying after this change:

  "64cdf43d-8d22-4e37-8607-c1f154d29ef5": {
    "description": null,
    "name": "new-connection",
    "service_id": "64cdf43d-8d22-4e37-8607-c1f154d29ef5",
    "status": "under provisioning"
  },

30min later the result is the same.

It seems the rollback failed and made the L2VPN to become inconsistent

[usmanazFIU]

to reproduce this issue create a l2vpn between amlight.net:MIA-MI1-SW14:23 and amlight.net:MIA-MI1-SW17:15.
after l2vpn is created change VLAN of one of the endpoints to a VLAN that is not available. the PATCH requests performs a rollback but deletes the endpoints in result. to check this your can query the l2vpn using GET /l2vpn and the response would show no endpoints:

"64cdf43d-8d22-4e37-8607-c1f154d29ef5": {
"description": null,
"name": "new-connection",
"service_id": "64cdf43d-8d22-4e37-8607-c1f154d29ef5",
"status": "under provisioning"
},

[usmanazFIU]

issue fixed in PR: #520