git kill branchname

@charlierudolph Aaaaahhhh, for some reason some commits meant for this PR ended up in an already merged PR. I was messing around with `git extract` while being distracted on the resource planning call, so that's my (super lame) excuse... Anyways, please take a look at https://github.com/Originate/git-town/commit/738e3e76158a4803c5695abf71349b21d02033f5, and comment there. I will implement the corresponding fixes in this pull request, and once this gets merged its all going to be kind of okay again...  :smile: 
I understand and agree with the idea of checking for side effects, but I want to be able to see the (bad) logic that allowed that to happen.

In this case we have a  `good-feature` branch, and run `git kill` on the main branch.The only logic I can come up with where the  `good-feature` branch would be deleted, is if git-kill removes all feature branches or is hard wired to always kill the `good-feature` branch. In that case many other tests would fail so I don't think that needs to be tested.