How do criss-cross merges arise in Git?

Question

I have been going through the, \"git merge-base\", man page and I can\'t understand how multiple merge bases develop. Specifically, I\'m hung up on the following illustratio

Answer 1

This happens when the other developer fetches commits from you, you fetch from them, and then you both merge each other's branches into your own after you've both fetched. That can happen, it's not an error state.