How does that work if there's a conflict? Whether or not there's a hash involved, you still have to manually apply the patch to each branch, would you not? If there's no conflict, merging each branch up in git is not hard at all, but it's still a tedious extra 'n - 1' operations that you don't need in chezmoi.
For example, say I have a line "export FOO=bar" in my .bashrc on one machine and "export FOO=baz" on another. If I then indent the line on the bar branch and try to merge to the other one, something has to tell the baz branch that the right line is both differences: " export FOO=baz". Except the conflict may not be so obvious to resolve as that! And whatever you do, you'll either have a "trellis" of 'n' branches if you merge, or 'n' parallel linear branches if you cherry pick everything. Both of those history layouts quickly become very hard (to me at least) to make sure they all contain everything they should and nothing they shouldn't.
Whereas with chezmoi, the bashrc file is a template that is the same on all machines that simply says "export FOO={{ fooval }}" and chezmoi does the templating. So you can just indent the line and fast-forward/apply on other machines and that's it.
Also, the conflict resolution is just another patch (Pijul patches aren't just regular diffs, they have a lot more information), so should you decide to merge it back upstream after all, you can also cherry-pick the conflict resolution along with the conflicting patch, and also without changing the hash.
For example, say I have a line "export FOO=bar" in my .bashrc on one machine and "export FOO=baz" on another. If I then indent the line on the bar branch and try to merge to the other one, something has to tell the baz branch that the right line is both differences: " export FOO=baz". Except the conflict may not be so obvious to resolve as that! And whatever you do, you'll either have a "trellis" of 'n' branches if you merge, or 'n' parallel linear branches if you cherry pick everything. Both of those history layouts quickly become very hard (to me at least) to make sure they all contain everything they should and nothing they shouldn't.
Whereas with chezmoi, the bashrc file is a template that is the same on all machines that simply says "export FOO={{ fooval }}" and chezmoi does the templating. So you can just indent the line and fast-forward/apply on other machines and that's it.