Code review comment for lp:~axwalk/juju-core/instances-arch-preference

I feel like we're missing some tests here. Otherwise looking good.

https://codereview.appspot.com/94530045/diff/1/environs/instances/image_test.go
File environs/instances/image_test.go (right):

https://codereview.appspot.com/94530045/diff/1/environs/instances/image_test.go#newcode194
environs/instances/image_test.go:194: },
Could use a few more tests here, I think.

https://codereview.appspot.com/94530045/diff/1/juju/arch/arch.go
File juju/arch/arch.go (right):

https://codereview.appspot.com/94530045/diff/1/juju/arch/arch.go#newcode36
juju/arch/arch.go:36: PPC64: {64},
Nice, thanks for this.

https://codereview.appspot.com/94530045/