The following sequence of steps teaches you how to move ROS packages from one (e.g. private) into another (e.g. public) repository while preserving the history at the same time.
  * git clone new-repos-uri
  * cd into new repos directory
  * git remote add src old-repos-uri
  * git fetch src
  * git checkout src/master -b tmp-branch
  * Do the magic filter command:
    <code>
    git filter-branch -f --tree-filter 'find . -maxdepth 1 -not -name . -a -not -name cool_package_name -a -not -name .git -exec rm -r {} \;'
    </code> 
    //The above command basically removes in every revision everything but the directories .git and cool_package_name.//
  * git checkout master
  * git merge tmp-branch
  * git filter-branch --prune-empty -f
  * git push