in dhcp-agent log i see

2014-09-03 23:03:15.665 30015 TRACE neutron.agent.dhcp_agent Command: ['sudo', '/usr/bin/neutron-rootwrap', '/etc/neutron/rootwrap.conf', 'ip', 'netns', 'exec', 'qdhcp-45916c72-e0ce-4049-bd82-08dc00e16fd2', 'ip', 'addr', 'show', 'tapaa860f85-c0', 'permanent', 'scope', 'global']
2014-09-03 23:03:15.665 30015 TRACE neutron.agent.dhcp_agent Exit code: 1
2014-09-03 23:03:15.665 30015 TRACE neutron.agent.dhcp_agent Stdout: ''
2014-09-03 23:03:15.665 30015 TRACE neutron.agent.dhcp_agent Stderr: 'Device "tapaa860f85-c0" does not exist.\n'

but manauly run

 sudo ip netns exec qdhcp-45916c72-e0ce-4049-bd82-08dc00e16fd2 ip addr show tapaa860f85-c0 permanent scope global 
270: tapaa860f85-c0: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default
    link/ether fa:16:3e:aa:43:ac brd ff:ff:ff:ff:ff:ff
    inet 10.1.0.2/24 brd 10.1.0.255 scope global tapaa860f85-c0
       valid_lft forever preferred_lft forever
    inet 169.254.169.254/16 brd 169.254.255.255 scope global tapaa860f85-c0
       valid_lft forever preferred_lft forever

whats going on?