Merging adjacent deleted lines?

Say I have a file that started out with the following content :

line1 line2 line3 line4

I create a branch, which deletes line2.  Someone else's branch deletes line 3.

When I merge those two branches, the conflict looks like :

line1 <<<<<<< HEAD:lines line3 ======= line2

line4

Which in my cursory overview, looked an awful lot like the obvious merge resolution ought to be

line1 line3 line4

After all - I know I want to delete line 2, and wasn't aware of the other person deleting line 3.

It was only later that we discovered that the merge was broken and both lines should have been deleted. Thinking about it, I guess that the conflict if the other branch _hadn't_ deleted line 3 would have looked something like

line1 <<<<<<< HEAD:lines ======= line2

line3 line4

 - which wouldn't have resulted in a conflict anyway.

So, it looks like I need to be way more careful when merging conflicts. Which leads me to - what tools do you use when studying conflicts like that? git blame seems the obvious one, for getting the context of each deletion, but it seems like I need to run it once as git blame HEAD lines, and once as git blame MERGE_HEAD lines. Is there something a little more integrated for comparing the origin of each change from both merge branches simultaneously?

Would welcome any thoughts on how you guys approach conflict-resolution -Jon