Description of problem:
On OSP14 with ODL - Build of instance aborted: Failed to allocate the network - neutron.agent.dhcp.agent unable to reload_allocations dhcp

Version-Release number of selected component (if applicable):
OSP14   -p 2018-11-21.2

How reproducible:
Sometimes

Steps to Reproduce:
1. Install OSP14 + ODL
2. Spawn a VM. 

You can use this script:
https://code.engineering.redhat.com/gerrit/gitweb?p=Neutron-QE.git;a=blob;f=Scripts/create_multi_topology.sh

For example:
./create_multi_topology.sh -q -i rhel75 -t mvi -c YES -e skip -n 2 -v 1

Actual results:
openstack server list --all
+--------------------------------------+-----------------+--------+----------+--
| ID                                   | Name            | Status | Networks | Image  | Flavor      |
+--------------------------------------+-----------------+--------+----------+--
| 429dff3a-236d-4072-8b7a-5530c9b3a492 | rhel75_vm1_net1 | ERROR  |          | rhel75 | rhel_flavor |
+--------------------------------------+-----------------+--------+----------+--

Build of instance 429dff3a-236d-4072-8b7a-5530c9b3a492 aborted: Failed to allocate the network(s), not rescheduling.', u'code': 500, u'details': u'  File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 1929, in _do_build_and_run_instance\n    filter_properties, request_spec)\n  File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 2186, in _build_and_run_instance\n    reason=msg)\n', u'created': u'2018-11-27T09:57:43Z'


On controller-1 the the VM networks cannot start (status=DOWN):


*** /var/log/containers/neutron/dhcp-agent.log ***


ERROR neutron.agent.dhcp.agent  Unable to reload_allocations dhcp for 13c1f9bc-73e9-4441-a2c4-c00262c94de8.: 
ProcessExecutionError: Exit code: 125; Stdin: ; Stdout: neutron-dnsmasq-qdhcp-13c1f9bc-73e9-4441-a2c4-c00262c94de8
; Stderr: Error response from daemon: removal of container neutron-dnsmasq-qdhcp-13c1f9bc-73e9-4441-a2c4-c00262c94de8 is already in progress
/usr/bin/docker-current: Error response from daemon: Conflict. 
The container name "/neutron-dnsmasq-qdhcp-13c1f9bc-73e9-4441-a2c4-c00262c94de8" is already in use by container a35399a0114e712e912105e12639522412aecfb9eaaf5a21b1586e1c0cf88b2c. 
You have to remove (or rename) that container to be able to reuse that name..

Acquired semaphore "dhcp-agent-network-lock-49b1c270-a2c1-4caf-b328-20e1951ed746" lock /usr/lib/python2.7/site-packages/oslo_concurrency/lockutils.py:212
Releasing semaphore "dhcp-agent-network-lock-49b1c270-a2c1-4caf-b328-20e1951ed746" lock /usr/lib/python2.7/site-packages/oslo_concurrency/lockutils.py:228
Lock "_check_child_processes" acquired by "neutron.agent.linux.external_process._check_child_processes" :: waited 0.000s inner /usr/lib/python2.7/site-packages/oslo_concurrency/lockutils.py:273
Lock "_check_child_processes" released by "neutron.agent.linux.external_process._check_child_processes" :: held 0.002s inner /usr/lib/python2.7/site-packages/oslo_concurrency/lockutils.py:285

Acquired semaphore "dhcp-agent-network-lock-bb294f07-63a6-4586-a4fc-ae541843f690" lock /usr/lib/python2.7/site-packages/oslo_concurrency/lockutils.py:212
Trigger reload_allocations for port 
admin_state_up=True, allowed_address_pairs=[], binding:host_id=, binding:profile=, binding:vif_details=, binding:vif_type=unbound, binding:vnic_type=normal, created_at=2018-11-27T09:51:35Z, description=, device_id=429dff3a-236d-4072-8b7a-5530c9b3a492, device_owner=, extra_dhcp_opts=[], fixed_ips=[{u'subnet_id': u'd743ec94-34fb-4739-b043-fa1619a14761', u'ip_address': u'10.0.1.9'}, {u'subnet_id': u'8f34659f-d947-498f-b0de-51f34b37e859', u'ip_address': u'2001::f816:3eff:fe57:2b8f'}], id=6a9e9751-9ed1-4ba7-9f4d-dca8b26a2766, mac_address=fa:16:3e:57:2b:8f, name=, network_id=bb294f07-63a6-4586-a4fc-ae541843f690, port_security_enabled=True, project_id=10b35bdd64ed47e2ad76f4f865e7d914, revision_number=1, security_groups=[u'7c7e236b-7ee3-45b4-9218-4afad2cd2a14'], status=DOWN, tags=[], tenant_id=10b35bdd64ed47e2ad76f4f865e7d914, updated_at=2018-11-27T09:51:35Z

Calling driver for network: bb294f07-63a6-4586-a4fc-ae541843f690 action: reload_allocations call_driver /usr/lib/python2.7/site-packages/neutron/agent/dhcp/agent.py:135
Building host file: /var/lib/neutron/dhcp/bb294f07-63a6-4586-a4fc-ae541843f690/host _output_hosts_file /usr/lib/python2.7/site-packages/neutron/agent/linux/dhcp.py:695
Done building host file /var/lib/neutron/dhcp/bb294f07-63a6-4586-a4fc-ae541843f690/host _output_hosts_file /usr/lib/python2.7/site-packages/neutron/agent/linux/dhcp.py:734
Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-bb294f07-63a6-4586-a4fc-ae541843f690', 'ip', 'addr', 'show', 'tapb83b453f-f6'] execute_rootwrap_daemon /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:103
Running command (rootwrap daemon): ['kill', '-HUP', '540366'] execute_rootwrap_daemon /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:103
Reloading allocations for network: bb294f07-63a6-4586-a4fc-ae541843f690 reload_allocations /usr/lib/python2.7/site-packages/neutron/agent/linux/dhcp.py:524
Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-bb294f07-63a6-4586-a4fc-ae541843f690', 'ip', '-4', 'route', 'list', 'dev', 'tapb83b453f-f6'] execute_rootwrap_daemon /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:103
Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qdhcp-bb294f07-63a6-4586-a4fc-ae541843f690', 'ip', '-6', 'route', 'list', 'dev', 'tapb83b453f-f6'] execute_rootwrap_daemon /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:103
Releasing semaphore "dhcp-agent-network-lock-bb294f07-63a6-4586-a4fc-ae541843f690" lock /usr/lib/python2.7/site-packages/oslo_concurrency/lockutils.py:228
...
Trigger reload_allocations for port
admin_state_up=True, allowed_address_pairs=[], binding:host_id=compute-1.localdomain, binding:profile=, binding:vif_details=, binding:vif_type=unbound, binding:vnic_type=normal, created_at=2018-11-27T09:51:35Z, description=, device_id=429dff3a-236d-4072-8b7a-5530c9b3a492, device_owner=compute:nova, extra_dhcp_opts=[], fixed_ips=[{u'subnet_id': u'd743ec94-34fb-4739-b043-fa1619a14761', u'ip_address': u'10.0.1.9'}, {u'subnet_id': u'8f34659f-d947-498f-b0de-51f34b37e859', u'ip_address': u'2001::f816:3eff:fe57:2b8f'}], id=6a9e9751-9ed1-4ba7-9f4d-dca8b26a2766, mac_address=fa:16:3e:57:2b:8f, name=, network_id=bb294f07-63a6-4586-a4fc-ae541843f690, port_security_enabled=True, project_id=10b35bdd64ed47e2ad76f4f865e7d914, revision_number=2, security_groups=[u'7c7e236b-7ee3-45b4-9218-4afad2cd2a14'], status=DOWN, tags=[], tenant_id=10b35bdd64ed47e2ad76f4f865e7d914, updated_at=2018-11-27T09:51:37Z
...
Trigger reload_allocations for port 
admin_state_up=True, allowed_address_pairs=[], binding:host_id=compute-1.localdomain, binding:profile=, binding:vif_details=, binding:vif_type=ovs, binding:vnic_type=normal, created_at=2018-11-27T09:51:35Z, description=, device_id=429dff3a-236d-4072-8b7a-5530c9b3a492, device_owner=compute:nova, extra_dhcp_opts=[], fixed_ips=[{u'subnet_id': u'd743ec94-34fb-4739-b043-fa1619a14761', u'ip_address': u'10.0.1.9'}, {u'subnet_id': u'8f34659f-d947-498f-b0de-51f34b37e859', u'ip_address': u'2001::f816:3eff:fe57:2b8f'}], id=6a9e9751-9ed1-4ba7-9f4d-dca8b26a2766, mac_address=fa:16:3e:57:2b:8f, name=, network_id=bb294f07-63a6-4586-a4fc-ae541843f690, port_security_enabled=True, project_id=10b35bdd64ed47e2ad76f4f865e7d914, revision_number=3, security_groups=[u'7c7e236b-7ee3-45b4-9218-4afad2cd2a14'], status=DOWN, tags=[], tenant_id=10b35bdd64ed47e2ad76f4f865e7d914, updated_at=2018-11-27T09:51:38Z



Expected results:
VM should be up and connected to the network.

Additional info:
Might be related to u/s bug: https://bugs.launchpad.net/cloud-archive/+bug/1763442