git force merge branch
# Migrate to the branch you want to merge into git checkout <branch_name> # Merge branch_b into branch you're in git merge branch_b # Force merge if the branches have unrelated histories. This means # you must have previously gotten an error message like this # 'fatal: refusing to merge unrelated histories' when you try to do # normal merge with the command above. git merge -X theirs branch_b --allow-unrelated-histories