title: Merge 2 different git repositories with nearly exact content
body: <p>Right now I've two different repositories.
  Repo 1: only the "core" and some "sys" modules. 
  Repo 2: Got also "core", "sys" and also a lot of other stuff.
  The problem is that the second repo isn't tracking or uploading any changes of core or sys modules and I've made a lot of changes in there. Core and sys didn't have had the same stage as core and sys had before I made these changes.</p>
  
  <p>Now I wan't to sync "core" and "sys" from repo 2 with repo 1 and I does not have any idea of a slight solution.</p>