[17.12] update vndr of swarmkit to a7680ec

[andrewhsu]

brings in this change:

• [17.12] Fix IP overlap with empty EndpointSpec moby/swarmkit#2513 [17.12] Fix IP overlap with empty EndpointSpec

comparison of changes on the engine: moby/swarmkit@7598f7a...a7680ec

comparison of changes on the cli: moby/swarmkit@de950a7...a7680ec

[dperny]

the changes to protobuf are just a weird import path changing thing. not sure how they got introduced, but they're part of a higher-level repository so vendoring that package isn't a concern, and if this builds fine then it works.

[thaJeztah]

LGTM

[thaJeztah]

Not sure what went wrong in the s390x CI;

01:56:34 ----------------------------------------------------------------------
01:56:34 FAIL: docker_cli_swarm_test.go:1539: DockerSwarmSuite.TestSwarmNetworkIPAMOptions
01:56:34 
01:56:34 [d8ccc6685ba4c] waiting for daemon to start
01:56:34 [d8ccc6685ba4c] daemon started
01:56:34 
01:56:34 docker_cli_swarm_test.go:1549:
01:56:34     c.Assert(strings.TrimSpace(out), checker.Contains, "com.docker.network.ipam.serial:true")
01:56:34 ... obtained string = "map[foo:bar]"
01:56:34 ... substring string = "com.docker.network.ipam.serial:true"
01:56:34 
01:56:34 [d8ccc6685ba4c] exiting daemon

[anshulpundir]

Also include moby/swarmkit#2519 in this ? @andrewhsu

[sebbrandt87]

What about the failing ce-tests-s390x?