Data race in new TestKillWaitForModels_WaitsForControllerMachines test

[Martin Packman]

The newly added test as part of bug 1642295 trips the data race detector in CI:

<http://reports.vapour.ws/releases/issue/584a7c0a749a561094912ab6>

WARNING: DATA RACE
Read by goroutine 57:
  runtime.mapaccess1_faststr()
      /usr/lib/go-1.6/src/runtime/hashmap_fast.go:193 +0x0
  github.com/juju/juju/cmd/juju/controller_test.(*fakeDestroyAPI).ModelStatus()
      /home/ubuntu/juju-core_2.1-rc1/src/github.com/juju/juju/cmd/juju/controller/destroy_test.go:111 +0x345
  github.com/juju/juju/cmd/juju/controller.newData()
      /home/ubuntu/juju-core_2.1-rc1/src/github.com/juju/juju/cmd/juju/controller/killstatus.go:71 +0x3db
  github.com/juju/juju/cmd/juju/controller.newTimedStatusUpdater.func1()
      /home/ubuntu/juju-core_2.1-rc1/src/github.com/juju/juju/cmd/juju/controller/killstatus.go:50 +0x126
  github.com/juju/juju/cmd/juju/controller.(*killCommand).WaitForModels()
      /home/ubuntu/juju-core_2.1-rc1/src/github.com/juju/juju/cmd/juju/controller/kill.go:199 +0x112
  github.com/juju/juju/cmd/juju/controller.KillWaitForModels()
      /home/ubuntu/juju-core_2.1-rc1/src/github.com/juju/juju/cmd/juju/controller/export_test.go:145 +0xb6
  github.com/juju/juju/cmd/juju/controller_test.(*KillSuite).TestKillWaitForModels_WaitsForControllerMachines.func1()
      /home/ubuntu/juju-core_2.1-rc1/src/github.com/juju/juju/cmd/juju/controller/kill_test.go:172 +0xc2

Previous write by goroutine 59:
  runtime.mapassign1()
      /usr/lib/go-1.6/src/runtime/hashmap.go:429 +0x0
  github.com/juju/juju/cmd/juju/controller_test.(*KillSuite).TestKillWaitForModels_WaitsForControllerMachines()
      /home/ubuntu/juju-core_2.1-rc1/src/github.com/juju/juju/cmd/juju/controller/kill_test.go:181 +0x39b
  runtime.call32()
      /usr/lib/go-1.6/src/runtime/asm_amd64.s:472 +0x3d
  reflect.Value.Call()
      /usr/lib/go-1.6/src/reflect/value.go:303 +0xcd
  gopkg.in/check%2ev1.(*suiteRunner).forkTest.func1()
      /home/ubuntu/juju-core_2.1-rc1/src/gopkg.in/check.v1/check.go:772 +0x5d1
  gopkg.in/check%2ev1.(*suiteRunner).forkCall.func1()
      /home/ubuntu/juju-core_2.1-rc1/src/gopkg.in/check.v1/check.go:666 +0x80

[Mick Gregg (macgreagoir)]

PR https://github.com/juju/juju/pull/6681