Bump to golang 1.12.9

[thaJeztah]

Did the bump in two steps, so that I can cherry-pick the intermediate 1.11.13 bump into older branches

[thaJeztah]

ping @dperny PTAL

[thaJeztah]

Weird failures; is Go 1.12 truncating strings using an ellipsis?

--- FAIL: TestTemplatedConfig (0.01s)
    getter_test.go:562: 
        	Error Trace:	getter_test.go:562
        	Error:      	Error message not equal:
        	            	expected: "failed to expand templated config templatedconfig: template: expansion:1:13: executing \"expansion\" at <secret \"unknowntarge...>: error calling secret: secret target unknowntarget not found"
        	            	actual  : "failed to expand templated config templatedconfig: template: expansion:1:13: executing \"expansion\" at <secret \"unknowntarget\">: error calling secret: secret target unknowntarget not found"

oh; the reverse actually; it's looking for <secret \"unknowntarge...>, but gets <secret \"unknowntarget\">

[thaJeztah]

time="2019-08-19T21:11:05Z" level=debug msg="(*worker).Update" len(assignments)=6
time="2019-08-19T21:11:05Z" level=debug msg="(*worker).reconcileSecrets" len(removedSecrets)=2 len(updatedSecrets)=0
time="2019-08-19T21:11:05Z" level=debug msg="(*worker).reconcileConfigs" len(removedConfigs)=2 len(updatedConfigs)=0
time="2019-08-19T21:11:05Z" level=debug msg="(*worker).reconcileTaskState" len(removedTasks)=2 len(updatedTasks)=0
PASS
time="2019-08-19T21:11:05Z" level=error msg="task manager failed to report status to agent" error="database not open" module=taskmanager service.id= task.id=task-2
panic: Log in goroutine after TestWorkerUpdate has completed

goroutine 1175 [running]:
testing.(*common).logDepth(0xc00019a100, 0xc0000396a0, 0x1d, 0x3)
	/usr/local/go/src/testing/testing.go:634 +0x51a
testing.(*common).log(...)
	/usr/local/go/src/testing/testing.go:614
testing.(*common).Log(0xc00019a100, 0xc00006fb00, 0x1, 0x1)
	/usr/local/go/src/testing/testing.go:642 +0x79
github.com/docker/swarmkit/agent.(*mockTaskController).Remove(0xc00020a780, 0x13b6f40, 0xc0000b4010, 0x13b6f40, 0xc0000b4010)
	/home/circleci/.go_workspace/src/github.com/docker/swarmkit/agent/worker_test.go:604 +0x8e
github.com/docker/swarmkit/agent.reconcileTaskState.func1(0xc0004dac60)
	/home/circleci/.go_workspace/src/github.com/docker/swarmkit/agent/worker.go:270 +0x137
created by github.com/docker/swarmkit/agent.reconcileTaskState
	/home/circleci/.go_workspace/src/github.com/docker/swarmkit/agent/worker.go:313 +0x1a6f
FAIL	github.com/docker/swarmkit/agent	4.244s
make: *** [coverage] Error 1
Exited with code 2

Relates to golang/go#29388, may need something like moby/moby#39197

[thaJeztah]

Error is triggered by https://github.com/docker/swarmkit/blob/486ad69951868792367a503042ef3f55b399cc40/agent/worker.go#L313

Which calls closemanager in a goroutine, where the logging can happen https://github.com/docker/swarmkit/blob/486ad69951868792367a503042ef3f55b399cc40/agent/worker.go#L259-L277

[thaJeztah]

interestingly this commit 596e0f9 removed the go routine when starting closemanager, but this commit added it back 6379ef0 (without removing the new goroutine inside closemanager)

[codecov]

Codecov Report

Merging #2880 into master will decrease coverage by 0.04%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master    #2880      +/-   ##
==========================================
- Coverage   62.22%   62.17%   -0.05%     
==========================================
  Files         139      139              
  Lines       22346    22345       -1     
==========================================
- Hits        13904    13893      -11     
- Misses       6962     6969       +7     
- Partials     1480     1483       +3

[dperny]

thank you based sebastiaan 🙌 💯 🙌