test that suggests tags arent fully peeled during push

This adds a (currently failing) unit test to illustrate an apparent deficiency with push.

This adds two annotated tags to the `push_src` test repository:

* `tag-tag` (eeea4f...) which is a tag to another annotated tag 36f79b...
* `tag-commit-two` (36f79b...) which is a tag to commit d9b63a...

Pushing `refs/tags/tag-tag` fails as it appears to neglect to include the intermediate tag in the pack.