By David Luhman
The Drupal UPGRADE.txt file and upgrade handbook page provide a lot of good information and procedures to perform a major upgrade (ex. 6.x => 7.x).
However, if you're looking to manage your Drupal 7 installation using Git, the upgrade guides don't provide Git-specific advice.
Here's a procedure I found useful when upgrading Drupal 6 to Drupal 7 using Git.
First, clone the Drupal 7 git repository using this :
git clone git://github.com/drupal/drupal.git