Code review comment for lp:~themue/juju-core/go-worker-firewaller-machines

Very close to LGTM, but I'd like to see more testing of the error paths.
What happens when zookeeper goes down, for example?
And I'm still unhappy about the non-thread-safe access to firewaller
variables in the tests.

https://codereview.appspot.com/6374069/diff/12001/worker/firewaller/firewaller.go
File worker/firewaller/firewaller.go (right):

https://codereview.appspot.com/6374069/diff/12001/worker/firewaller/firewaller.go#newcode145
worker/firewaller/firewaller.go:145: // Had been an error, so end the
loop.
// The watcher terminated prematurely, so end the loop.

https://codereview.appspot.com/6374069/diff/12001/worker/firewaller/firewaller_test.go
File worker/firewaller/firewaller_test.go (right):

https://codereview.appspot.com/6374069/diff/12001/worker/firewaller/firewaller_test.go#newcode81
worker/firewaller/firewaller_test.go:81: c.Assert(addedMachines,
DeepEquals, allMachines)
c.Assert(allMachines, DeepEquals, addedMachines)

https://codereview.appspot.com/6374069/diff/12001/worker/firewaller/firewaller_test.go#newcode91
worker/firewaller/firewaller_test.go:91: c.Assert(addedMachines,
DeepEquals, allMachines)
c.Assert(allMachines, DeepEquals, addedMachines)

https://codereview.appspot.com/6374069/