Odd problems trying to build an orphaned branch

I am trying to create an orphaned branch that contains the linux-3.12.y branch from linux-stable. Each time I try a method to make this work I encounter a blocker that halts my progress.

I expect that at least one of these is a bug, but I am not sure.

Here is what I did. I have read the docs and tried a huge pile of suggestions. How is this supposed to be done?

I am using git version 2.6.2.402.g2635c2b. It passes all the tests.

I created an orphan branch from 3.12-rc1. I then used git format-patch to generate patches from 3.12-rc1 to HEAD. (Over 7000 patches.) I use git am to apply them to the orphan branch. At patch 237 it fails to apply. (It appears the patch is from a block of code added with a merge commit, but it is somewhere in the middle of the block.)

Are merge commits supposed to screw up git-format-patch?

I also tried using clone with depth and --single-branch set. It ignored the depth setting and gave me the whole branch all the way back to 2.6.x.

All the examples of shallow clones use depth=1. Is it broken for values bigger than 1 or am I missing something?

I tried using graft and filter-branch. None of the descriptions are very clear. None of them worked either. Filter-branch died on a commit somewhere in 2.6 land that had no author. (Which is outside of the commits I want to keep.)

I tried creating an orphan branch and using cherry-pick v3.12-rc1..linux-3.12.y. It blew up on the first merge commit it hit. I tried adding in "-m 1" to try to get it to pick a parent, but then it died on the first commit because it was not a merge.

Why is this so hard?

All I want to do is take a branch from linux-stable and create a branch that contains just the commits from where it was branched off of master until it hits HEAD. That is it. All the scripts that I have seen that claim to do just what I want break when it hits a merge or a bogus author. (How that got into linux-stable, I have no idea. The commit is 10 year old!)

Ideas? Do I need to create a new command? ("cake-cutter". Cut from commit..commit and make a new branch out of it.)