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:

    git filter-branch -f --tree-filter 'find . -maxdepth 1 -not -name . -a -not -name cool_package_name -a -not -name .git -exec rm -r {} \;'
    

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