Race in github.com/juju/juju/api/state.go

[Curtis Hovey]

As seen in
    http://reports.vapour.ws/releases/issue/572c9149749a5664afc0c132

There is a race in github.com/juju/juju/api/state between several functions. A recent example shows api/state involved

==================
WARNING: DATA RACE
Write by goroutine 122:
  github.com/juju/juju/api.(*state).setLoginResult()
      /home/ubuntu/juju-core_2.0-beta16/src/github.com/juju/juju/api/state.go:176 +0x7bd
  github.com/juju/juju/api.(*state).loginForVersion()
      /home/ubuntu/juju-core_2.0-beta16/src/github.com/juju/juju/api/state.go:128 +0x130b
  github.com/juju/juju/api.(*state).loginV3()
      /home/ubuntu/juju-core_2.0-beta16/src/github.com/juju/juju/api/state.go:46 +0xc5
  github.com/juju/juju/api.(*state).Login()
      /home/ubuntu/juju-core_2.0-beta16/src/github.com/juju/juju/api/state.go:36 +0xc2
  github.com/juju/juju/apiserver_test.(*loginSuite).TestOtherEnvironmentFromControllerOtherNotProvisioned()
      /home/ubuntu/juju-core_2.0-beta16/src/github.com/juju/juju/apiserver/admin_test.go:800 +0x68a
  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_2.0-beta16/src/gopkg.in/check.v1/check.go:772 +0x5d1
  gopkg.in/check%2ev1.(*suiteRunner).forkCall.func1()
      /home/ubuntu/juju-core_2.0-beta16/src/gopkg.in/check.v1/check.go:666 +0x80

Previous read by goroutine 280:
  github.com/juju/juju/api.(*state).BestFacadeVersion()
      /home/ubuntu/juju-core_2.0-beta16/src/github.com/juju/juju/api/apiclient.go:696 +0xd2
  github.com/juju/juju/api.(*state).Ping()
      /home/ubuntu/juju-core_2.0-beta16/src/github.com/juju/juju/api/apiclient.go:592 +0x62
  github.com/juju/juju/api.(*state).Ping-fm()
      /home/ubuntu/juju-core_2.0-beta16/src/github.com/juju/juju/api/apiclient.go:580 +0x3b
  github.com/juju/juju/api.callWithTimeout.func1()
      /home/ubuntu/juju-core_2.0-beta16/src/github.com/juju/juju/api/apiclient.go:564 +0x2a

A similar bug is https://bugs.launchpad.net/juju-core/+bug/1579057 that was fixed in May