[ostf] Assign floating IP failed in test, but actually assigned

Run OSTF test "Check network connectivity from instance via floating IP" separately from others.
Target component: Neutron

Can not assign floating ip to instance Please refer to OpenStack logs for more details.

Scenario:
1. Create a new security group (if it doesn`t exist yet).
2. Create router
3. Create network
4. Create subnet
5. Uplink subnet to router.
6. Create an instance using the new security group
in created subnet.
7. Create a new floating IP
FAILED on this step: 8. Assign the new floating IP to the instance. -
...

Actually Floating IP assigned to instance:

# nova floating-ip-list
+--------------+--------------------------------------+----------+-----------+
| Ip | Server Id | Fixed Ip | Pool |
+--------------+--------------------------------------+----------+-----------+
| 172.16.57.26 | 3cf8e90f-b344-4345-a09d-7057f1196f53 | 10.0.7.2 | net04_ext |
+--------------+--------------------------------------+----------+-----------+

ENV:
Juno on CentOS 6.5, Neutron with VLAN segmentation, QEMU, no additional components.
1 Controller
1 Compute
1 Cinder with LVM

VERSION:
  feature_groups:
    - mirantis
  production: "docker"
  release: "6.1"
  openstack_version: "2014.2.2-6.1"
  api: "1.0"
  build_number: "354"
  build_id: "2015-04-27_09-17-29"
  nailgun_sha: "2efc207e7156e362c2506b66e63b8bfa745d1153"
  python-fuelclient_sha: "2b311b3b82a1e2df1dc3484a0f37e282273cd988"
  astute_sha: "c1793f982fda7e3fc7b937ccaa613c649be6a144"
  fuel-library_sha: "6bdf783e2bffdce80ecffcca2915e6d32a8ccdd7"
  fuel-ostf_sha: "b38602c841deaa03ddffc95c02f319360462cbe3"
  fuelmain_sha: "01288380950bc89d572cf5902141c9a393ada950"

Diagnostic Snapshot: https://drive.google.com/file/d/0B6E70aHvCcRQOVZEVXNBMEQ4cE0/view?usp=sharing