Sometimes you may need to port some changes from DDA. It could be done via adding remote and cherry-picking.

tl;dr version

git remote add dda https://github.com/CleverRaven/Cataclysm-DDA
git fetch dda
git checkout -b ddamaster dda/master
git checkout ddamaster && git pull

Explained version

Setting up

Assuming you have a directory with BN named Cataclysm-BN, open a terminal there.

Add the remote tracking branch for DDA. Let’s name the branch dda (doesn’t need to be dda):

git remote add dda https://github.com/CleverRaven/Cataclysm-DDA

To download the contents of the new branch, it has to be fetched:

git fetch dda

This downloads all the content from the remote tracking branch. It shouldn’t take very long, because it doesn’t download the things common to both repos. Once fetched, you can merge, pull, checkout etc. the branches on the remote, but you have to prepend them with dda/, for example dda/master. It’s useful to have a local branch pointing to the remote tracking one:

git checkout -b ddamaster dda/master

This creates an ddamaster branch, which is basically DDA’s master branch. You can take other name instead of ddamaster.

Updating

The simplest way is:

git checkout ddamaster 
git pull

This shouldn’t result in any conflicts. If it did, you probably committed changes to the main branch. In this case you may want to back them up:

git checkout -b temp-branch-name

And reset the main branch to the remote:

git branch -f ddamaster dda/master

Contributing

# Switch to BN branch
git checkout main
# Update local content
git pull
# Create new branch for your changes
git checkout -b chainsaw-toothbrush-rebalance
# [do stuff with files]
...
# Commit the changes
git commit -a
# Upload your changes to your fork of Cataclysm (assuming its branch is named origin)
git push -u origin chainsaw-toothbrush-rebalance
# Go to BN's github and make a pull request

Porting

Porting is done with git cherry-pick. First, you need to find the hash of the merge commit, or the first and the last of the commits from the range you want to port. On github, those are on the right side of commit descriptions in a PR. You can use the full hash or the shortened version. In the examples, fafafaf is the merge commit, while a0a0a0a and b1b1b1b are the first and last commit from a range (order is important). Then, from a branch you are porting to, cherry-pick the merge commit or the range of commits:

# Merge commit
git cherry-pick fafafaf
# Commit range
git cherry-pick a0a0a0a..b1b1b1b

Resolve the conflicts (there will be many for non-trivial PRs and you’ll have to resolve most of them manually):

git mergetool

The above may require setting up a merge conflict resolving tool (TODO: describe how to do that). Then commit and push, as usual.