Revert "[backport 17.06] Fixes bug that mistook gw6 for gw."

[fcrisciani]

Reverts #1875

Signed-off-by: Flavio Crisciani flavio.crisciani@docker.com

[GordonTheTurtle]

Please sign your commits following these rules:
https://github.com/moby/moby/blob/master/CONTRIBUTING.md#sign-your-work
The easiest way to do this is to amend the last commit:

$ git clone -b "revert-1875-restore_17.06" git@github.com:docker/libnetwork.git somewhere
$ cd somewhere
$ git commit --amend -s --no-edit
$ git push -f

Amending updates the existing PR. You DO NOT need to open a new one.

[mavenugo]

LGTM.

We will reintroduce this patch once we figure out why this breaks Integration-cli tests.

[andrewhsu]

Before the revert, saw this error on builds:

[DockerDaemonSuite] FAIL: docker_cli_network_unix_test.go:1677: DockerDaemonSuite.TestDaemonRestartRestoreBridgeNetwork
[DockerDaemonSuite] 
[DockerDaemonSuite] [d4c2f01bc0001] waiting for daemon to start
[DockerDaemonSuite] [d4c2f01bc0001] daemon started
[DockerDaemonSuite] 
[DockerDaemonSuite] [d4c2f01bc0001] waiting for daemon to start
[DockerDaemonSuite] [d4c2f01bc0001] daemon started
[DockerDaemonSuite] 
[DockerDaemonSuite] docker_cli_network_unix_test.go:1733:
[DockerDaemonSuite]     t.Fatal(err)
[DockerDaemonSuite] ... Error: exit status 125
[DockerDaemonSuite] 
[DockerDaemonSuite] [d4c2f01bc0001] exiting daemon