There is one (though incomplete)! And it's called Mercurial. Since 5.4 released earlier this year, Mercurial is slowly gaining [1] the ability to operate on local Git repositories with its bundled git extension [2].

[1]: https://www.mercurial-scm.org/repo/hg/log?rev=keyword%28%27g... [2]: https://www.mercurial-scm.org/wiki/GitExtension