Iss827

I need some help with the tests.  I've added MkCommitsTest and RtCommitsTest, but they are ignored.  The RtCommitsTest requires some knowledge of the underlying test framework which I don't have.  Likewise, the MkCommitsTest is failing because there's something else going on which I'm not familiar with.  Considering the scope of this issue (it did not take 30 minutes), I could use a hand with completing this.
This is not a very useful check. Better if you try to obtain the `sha()` of the created `Commit` and see if it matches with the one you specified in line 63.