docker iptables and bridge not cleaned-up on shutdown

Hi,
Not sure if its bug or intended behavior.
When I bring up docker, it creates docker0 interface and installs some iptables rules. That's fine.
When the dockerd is stopped, docker0 interface still persists and default docker iptables rules are not removed.

If its not bug, I would like to know the reasoning behind it.
Thanks,
Ketan

Details follow:

• Docker started using
  dockerd

ifconfig output

docker0   Link encap:Ethernet  HWaddr 02:42:7f:68:63:d0
          inet addr:172.17.0.1  Bcast:172.17.255.255  Mask:255.255.0.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

iptables when docker is running

# iptables-save | grep -i docker
:DOCKER - [0:0]
-A PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
-A OUTPUT ! -d 127.0.0.0/8 -m addrtype --dst-type LOCAL -j DOCKER
-A POSTROUTING -s 172.17.0.0/16 ! -o docker0 -j MASQUERADE
-A DOCKER -i docker0 -j RETURN
:DOCKER - [0:0]
:DOCKER-ISOLATION - [0:0]
:DOCKER-USER - [0:0]
-A FORWARD -j DOCKER-USER
-A FORWARD -j DOCKER-ISOLATION
-A FORWARD -o docker0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o docker0 -j DOCKER
-A FORWARD -i docker0 ! -o docker0 -j ACCEPT
-A FORWARD -i docker0 -o docker0 -j ACCEPT
-A DOCKER-ISOLATION -j RETURN
-A DOCKER-USER -j RETURN

• stop the docker

• ifconfig when docker is not running

docker0   Link encap:Ethernet  HWaddr 02:42:7f:68:63:d0
          inet addr:172.17.0.1  Bcast:172.17.255.255  Mask:255.255.0.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

• iptables when docker is not running

# iptables-save | grep -i docker
:DOCKER - [0:0]
-A PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
-A OUTPUT ! -d 127.0.0.0/8 -m addrtype --dst-type LOCAL -j DOCKER
-A POSTROUTING -s 172.17.0.0/16 ! -o docker0 -j MASQUERADE
-A DOCKER -i docker0 -j RETURN
:DOCKER - [0:0]
:DOCKER-ISOLATION - [0:0]
:DOCKER-USER - [0:0]
-A FORWARD -j DOCKER-USER
-A FORWARD -j DOCKER-ISOLATION
-A FORWARD -o docker0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o docker0 -j DOCKER
-A FORWARD -i docker0 ! -o docker0 -j ACCEPT
-A FORWARD -i docker0 -o docker0 -j ACCEPT
-A DOCKER-ISOLATION -j RETURN
-A DOCKER-USER -j RETURN

docker info

Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 0
Server Version: 18.03.0
Storage Driver: vfs
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host macvlan null overlay
 Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: cfd04396dc68220d1cecbe686a6cc3aa5ce3667c.m (expected: cfd04396dc68220d1cecbe686a6cc3aa5ce3667c)
runc version: N/A (expected: 4fc53a81fb7c994640722ac585fa9ca548971871)
init version: N/A (expected: )
Kernel Version: 3.10.62-ltsi
Operating System: <unknown>
OSType: linux
Architecture: x86_64
CPUs: 2
Total Memory: 14.32GiB
Name: vm19
ID: J4TC:7QM4:S6UF:L6UW:WV2R:TPXC:STGV:MMJC:NSPF:H23A:ZMOA:25QY
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Labels:
Experimental: false
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false

WARNING: No cpu cfs quota support
WARNING: No cpu cfs period support

uname -a

Linux 3.10.62-ltsi #1 SMP PREEMPT x86_64 x86_64 x86_64 GNU/Linux

No source file or test entry point is identified in the report. Start by reproducing the shutdown behavior with dockerd, comparing docker0 and the iptables-save output before and after stopping it; done should establish whether these resources are intentionally retained and either document that behavior or define the required cleanup change.