I had some patches in one Git repository that I wanted to apply to a different repository. Here's a useful link I found on this :
http://stackoverflow.com/questions/327249/seeking-examples-of-workflow-u...
Here's what I did.
First, copy the original repository you want to get patch from. This may not be necessary in all cases, but in my case the original repository was on another machine, so this just puts everything on the same machine.
$ git clone ssh://me@example.com/repos/origRepo
$ cd origRepo