test that suggests tags arent fully peeled during push
push: handle tag chains correctly

When dealing with a chain of tags, we need to enqueue each of them
individually, which means we can't use `git_tag_peel` as that jumps
over the intermediate tags.

Do the peeling manually so we can look at each object and take the
appropriate action.
Merge pull request #1778 from libgit2/push_tag_to_tag_test

push: handle tag chains correctly