`bower.json` reset to first run, not initial value.

[rwjblue]

When running ember try:testall in ember-test-helpers (based on emberjs/ember-test-helpers#145), I noticed that the bower.json file after a run is being reset to the contents of the first scenario ran (ember-1.10 in our case).

[rwjblue]

I am not able to reproduce this today...

I'll chalk it up to user error and one to many 🍻 last night ;P