Display Git Status is a pretty simple plugin, all it needs is access to the shell_exec function and to be pointed at a git repository.
The plugin will not perform any state altering operations, it accesses the repository using read only methods to fetch information like branch name, last commit and status.
When the git repository is located (defaulting to wp-content, or overwritten via a setting) the plugin will add a new admin bar item with the git icon and the current branch name.
When your site has untracked changes the menu items background will turn red.
This is ideal as it gives you a small marker directly in the admin area that some changes have been made which you probably need to look into.
Additionally when accessing the plugins admin page you can see the result of the git status command, and the last commit applied to your site.
Screenshots
Display Git Status settings page, here you can set the repository location, additionally the git status and last commit information.
When your site and repository and are in sync you can see the branch name in the admin bar.
And when your site and repository are divergent the admin bar items background changes to red, alerting you of a problem.