This is related to my fix in#658. Apparently, MacOS adds a gitexecutable that is just a stub which displays an error. This gets pastthe try/except I added in#658, and allows all of the GitPythoncomponents to be imported, but since the executable is not *actually*git, it results in an exception when ``refresh()`` attemepts to run a``git version``.

Fix small typo and slightly reword docstring.

I found the extra 8 spaces at the start of the examples in the tutorialto be distracting. The Sphinx dedent option removes these extra spacesfrom the rendered code blocks.I also got a warning about the shell code example not being lexed asPython, so I converted this to an explicit shell code block.

Using "import as" is normally a time saver but for usability of the documentation, please consider removing osp and join with fully qualified calls for better snippet readability.