>[Currently](https://github.com/libgit2/libgit2sharp/blob/reflog-refactor/LibGit2Sharp.Tests/ReflogFixture.cs#L34-L41), trying to read a nonexistent reflog throws `InvalidSpecificationException`

I *think* that the InvalidSpecificationException may be explained by the fact that top level references are expected to be in uppercase (eg. HEAD, FETCH_HEAD).

I'd prefer if we could find a way to not make this method `public`. @dahlbyk any proposal?