At worst, just download the latest stable release from
http://git.or.cz/ and build from source.
+For details on building the programs in this package, see
+the file, README-hacking.
+
Use the latest upstream sources
===============================
Now use git format-patch, as above.
+Amending the most recent change on your private branch
+======================================================
+Let's say you've just committed a change on your private
+branch, and then realize that something about it is not right.
+It's easy to adjust:
+ edit your files # this can include running "git add NEW" or "git rm BAD"
+ git commit --amend -e -a
+ git format-patch --stdout --signoff HEAD~1 > your-branch.diff
+That replaces the most recent commit with the revised one.