Re: impure renames / history tracking

quoted

Yes, but imo a poor one, as you're losing all the history.

Well, not per se. You might keep the original 'detail' branch. It's a 
terminal branch obviously, you can't pull master's changes to it once 
the aggregate patch goes into master. But you can keep it around.

Actually, you can!  That's what the "ours" merge stratgy is for!
It creates a merge whose result is a verbatim copy of the first parent.

The intended use is for when you've cherry-picked or otherwise manually
merged everything interesting from a branch and want to tie up the loose
end so you can delete the branch name.