Merge Git Repositories and Preseve Commit History by Scott W Bradley

move-merge-git-repositories-and-keep-history

# ...First create a new empty repository on github named 'simpsons'...

# Clone all the repos to work with
$ cd ~/src
$ git clone git@github.com:scottwb/homer.git
$ git clone git@github.com:scottwb/bart.git
$ git clone git@github.com:scottwb/simpsons.git

# Copy over homer to simpsons
$ cd homer
$ git remote rm origin
$ mkdir homer
$ git mv *.* homer/.
$ git commit -m "Prepare homer to merge into simpsons"
$ cd ../simpsons
$ git remote add homer ~/src/homer
$ git pull homer master
$ git remote rm homer
$ cd ..
$ rm -rf homer

# Copy over bart to simpsons
$ cd bart
$ git remote rm origin
$ mkdir bart
$ git mv *.* bart/.
$ git commit -m "Prepare bart to merge into simpsons"
$ cd ../simpsons
$ git remote add bart ~/src/bart
$ git pull bart master
$ git remote rm bart
$ cd ..
$ rm -rf bart

# Push simpsons back upstream to github
$ cd simpsons
$ git push

Original: http://scottwb.com/blog/2012/07/14/merge-git-repositories-and-preseve-commit-history/