git-fork

#!/bin/bash

framework=$1 
project=$2
remote=$3

if [[ ! ("$#" -eq 3)]]
then
  echo >&2 "Usage: $0 <framework-repo> <project-name> <project-repo>"
  exit 1
fi

echo "Cloning framework: $1"
echo "  into project $2"
echo "  with new origin repo $3"

git clone $framework $project
cd $project
git submodule init && \
  git submodule update && \
  git remote rename origin source && \
  git branch --track framework-source source/master && \
  git remote add origin $remote && \
  git push origin master && \
  git checkout framework-source && \
  git branch --force --set-upstream master origin/master && \
  git checkout master

The above script will:

1. Clone <framework-repo> into a <project-name> working directory
2. Create a framework-source branch that tracks the master branch at <framework-repo>
3. Point origin at <project-repo>
4. Push to origin/master
5. Set the master branch to track the master branch at <project-repo> master branch

From that point forward, you do all your work in branches, merge into master, push to origin, etc. just like always. Never commit or merge to framework-source. When you want to pull upstream changes into master:

1. git checkout master
2. git branch upstream-rebase
3. git checkout framework-source
4. git pull
5. git checkout upstream-rebase
6. git rebase framework-source
7. [fix merge conflicts and commit until branch is clean]
8. [check to make sure tests run and everything works as expected]
9. git checkout master
10. git merge upstream-rebase [which should be a fast-forward]
11. [make sure master passes the same tests as in step 8]
12. git branch -D upstream-rebase

It's not as painful as it looks, except for the conflict resolution, which is always a pain. Steps 1-6 could be pretty easily encapsulated in a shell script, but the rest is too potentially destructive to trust to an automated process.

It's been pointed out that this looks a lot like subtree merging, and it does. But the subtree strategy assumes you want to include the contents of an independent project in a subdirectory of your repo, and doesn't really help when you want to fork and pull from/to the root.