moving-commits-using-patches.md

How to move commits between two repos that don't share a commit history:

• I have two repos github.com/<my employer>/playbooks and github.com/roots/trellis
• github.com/<my employer>/playbooks has a directory wordpress/trellis
• wordpress/trellis in github.com/<my employer>/playbooks contains code from github.com/roots/trellis, has changes made but commited in github.com/<my employer>/playbooks/.git all tracked changes from upstream have been lost (github.com/<my employer>/playbooks/wordpress/trellis/.git was deleted).

We need to merge the latest changes in github.com/roots/trellis with whatever changes we staged for github.com/<my employer>/playbooks/wordpress/trellis

1. Clone git@github.com:roots/trellis.git

git clone git@github.com:roots/trellis.git

2. Find commit right before first commit on Ona side (Jan 5th 2017). Appears to be a6f0793579913ee9121ba4be445f430ef266d54c
3. Reset to that commit

cd trellis
git reset --hard a6f0793579913ee9121ba4be445f430ef266d54c

4. Create patch files out of the work done in git@github.com:<my employer>/playbooks.git that affect the wordpress/trellis dir.

cd ../playbooks
git log --pretty=format:"%h" --reverse wordpress/trellis | xargs -i git format-patch -1 {} wordpress/trellis > patch-order.out

5. Fix the paths in the patch files, since the patches will be applied to a repository where technically everyting in wordpress/trellis is in the root dir.

find . -iname "*.patch" -maxdepth 1 -exec sed -i -e 's/wordpress\/trellis\///g' {} \;

6. Move all the patch files to the newly cloned trellis repo

mkdir ../patches
mv *.patch ../patches/
mv patch-order.out ../patches/

7. One by one, using the order defined in the patch-order.out file. Apply the files on the git@github.com:roots/trellis.git clone.

cd ../trellis
git am --3way ../patches/<name of patch file>

If conflic occurs while patching, resolve then:

git add <file where conflict was resolved>
git am --resolve