How to Avoid Force Push and Rebase
What about Force Push?
In this class, destructive git operations such as force push (git push --force) and rebase (git rebase, git pull --rebase) are forbidden because they remove git history that is important for marking.
Force push should never be used in any case, because it will break every one else's git repo that is working on the same project.
What about Rebase?
Rebase is often used in very large open-source projects with 100s-1000s of developers such as the Linux kernel. It is used in these large projects to reduce the number of commits Linux kernel git repository that has over a million commits! It does this by "flattening" the pull request to a single commit. However, it is not appropriate for the assignments, labs, and projects in this course. In addition, github's pull request UI makes viewing the "flat" diff easy, even if the pull request itself is composed of several commits.
What to do: "warning: Pulling without specifying how to reconcile divergent branches is discouraged."
Make sure you are on the branch you want to pull to.
Use git pull --no-rebase instead of git pull. This will start the merge process. Make sure to edit any files with conflicts to make them the way you want them! Then add & commit.
Use git config pull.rebase false to have git remember this for the repository. Use git config --global pull.rebase false to have git remember this for all repositories.
What to do: "fatal: Not possible to fast-forward, aborting."
Try git pull --no-rebase as described in the previous section, or:
Use git fetch --all to download all of the remote branches, then git branch -a to see all of the branches. Find the name of the branch that is in conflict, it should be something like remotes/origin/source_branch_name.
Make sure you are on the branch you want to merge to, e.g.: git checkout destination_branch_name
Then, start the merge process with git merge remotes/origin/source_branch_name. Make sure to edit any files with conflicts to make them the way you want them! Then add & commit.
What to do: "refusing to merge unrelated histories"
Follow the steps from the previous section but add --allow-unrelated-histories argument to git merge:
git checkout destination_branch_name
git merge remotes/origin/source_branch_name --allow-unrelated-histories
Make sure to edit any files with conflicts to make them the way you want them! Then add & commit.