Description of problem:
when running os-net-config with the following configuration it silently fails to create br-dpdk0/1:
- type: ovs_user_bridge
  name: br-dpdk0
  mtu: 9000
  use_dhcp: false
  ovs_extra:
    - set Interface dpdk2 options:n_rxq_desc=2048
    - set Interface dpdk2 options:n_txq_desc=2048
  members:
    - type: ovs_dpdk_port
      rx_queue: 1
      name: dpdk2
      mtu: 9000
      members:
        - type: interface
          name: nic5

- type: ovs_user_bridge
  name: br-dpdk1
  mtu: 9000
  use_dhcp: false
  ovs_extra:
    - set Interface dpdk3 options:n_rxq_desc=2048
    - set Interface dpdk3 options:n_txq_desc=2048
  members:
    - type: ovs_dpdk_port
      rx_queue: 1
      name: dpdk3
      mtu: 9000
      members:
        - type: interface
          name: nic6

[root@compute-0 ~]# os-net-config -c /etc/os-net-config/config.yaml -m /etc/os-net-config/mapping.yaml
[root@compute-0 ~]# ip a | grep dpdk
[root@compute-0 ~]#


although is is matching documentation, only when changing to the following config it is creating the expected bridges with the extra configuration:
- type: ovs_user_bridge
  name: br-dpdk0
  mtu: 9000
  use_dhcp: false
  members:
    - type: ovs_dpdk_port
      ovs_extra:
        - set Interface dpdk2 options:n_rxq_desc=2048
        - set Interface dpdk2 options:n_txq_desc=2048
      rx_queue: 1
      name: dpdk2
      mtu: 9000
      members:
        - type: interface
          name: nic5

- type: ovs_user_bridge
  name: br-dpdk1
  mtu: 9000
  use_dhcp: false
  members:
    - type: ovs_dpdk_port
      ovs_extra:
        - set Interface dpdk3 options:n_rxq_desc=2048
        - set Interface dpdk3 options:n_txq_desc=2048
      rx_queue: 1
      name: dpdk3
      mtu: 9000
      members:
        - type: interface
          name: nic6

[root@compute-0 ~]# os-net-config -c /etc/os-net-config/config.yaml -m /etc/os-net-config/mapping.yaml
[root@compute-0 ~]# ip a | grep dpdk
61: br-dpdk0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 9000 qdisc fq_codel state UNKNOWN group default qlen 1000
62: br-dpdk1: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 9000 qdisc fq_codel state UNKNOWN group default qlen 1000
[root@compute-0 ~]# ovs-vsctl --columns=options list interface dpdk2
options : {dpdk-devargs="0000:82:00.2", n_rxq="1", n_rxq_desc="2048", n_txq_desc="2048"}
[root@compute-0 ~]# ovs-vsctl --columns=options list interface dpdk3
options : {dpdk-devargs="0000:82:00.3", n_rxq="1", n_rxq_desc="2048", n_txq_desc="2048"}


Version-Release number of selected component (if applicable):
[root@compute-0 ~]# os-net-config --version
14.2.1


How reproducible:
100%

Steps to Reproduce:
1. use the first configuration mentioned to run os-net-config
2. check if bridges are created
3.

Actual results:
os-net-config silently fails to create the expected bridges

Expected results:
bridges either created of failure doesn't go silently 

Additional info:
created the following lunchpad bug for the upstream docs https://bugs.launchpad.net/os-net-config/+bug/2067263