GIT has 2 types of tags, lightweight or not.  The branch option (-b) does not work on lightweight tags so it takes 2 operations to accomplish the clone and then the checkout on the lightweight branch.  One could argue that we only support non-lightweight tags, but I added it for completeness.

Yes,  "clones the buildpack URL and does a checkout with a branch" does test the second path.  The test name should be improved.