check out deletor branch
merge in editor branch
line 4 will cause a conflict. Open the file in kaleidoscope via git mergetool.
Notice how it seems like editor added line 2, when really deletor deleted it.
Also open the merge result in a text editor to see what git's auto-merge did. It correctly removes line 2 from the merge result.
I'm guessing its because editor's last commit is more recent, and the 3-way merge is comparing A to B by timestamp, rather than A to base and B to base.