What's the best way to merge external changes into my Git repo?

Question

I have a project in a Git repo and I have been sent changes that have been made outside of Git. These changes are based on an earlier version that I have been making changes to myself. What is the best way to merge these external files with mine?

Many thanks!

Answer 1

The best way is to tell git what commit they were based off of, to give you the best chance of an automatic merge.

1. git checkout <sha1 of the old commit> -b mybranch, to rewind your work tree and start a new branch.
2. If the changes were sent as a diff, use git-apply to apply them to the work tree, otherwise just put the updated files in.
3. Add and commit the files.
4. git checkout master, then git merge mybranch.

Answer 2

You'll want to act exactly as if you were working with these files, so commit them from the state of the earlier version you're talking about:

1. Create a branch at the commit you believe to be the base of the modified file
2. Add the modified file
3. Commit
4. Merge back the branch to your main development branch