`git patch-id --stable' vs quoted-printable

While poking around at the newish patchid indexing support in public-inbox[1], I noticed an inconsistency in how it seems to mishandle quoted-printable messages.

For instance, René's message can apply fine with `git am':

https://public-inbox.org/git/6727daf1-f077-7319-187e-ab4e55de3b2d@web.de/raw

However, note the blank context lines are truly blank, as in /^$/, not /^ $/. Running `git patch-id --stable' on the decoded content of that message gives me: a245e99dbd2ce6e319955569eb8a111cb044f474 And that's the value public-inbox indexes.

That patch ends up being commit fc0f8bcd64eb0a03a7098f72da9c4008bd48cf11 in git.git.

However, `git show fc0f8bcd64eb0a03a7098f72da9c4008bd48cf11 |git patch-id --stable' gives me: fcac4cf581e11b703c229a129072c95c79b68bf

So, I'm wondering if the search indexing code of public-inbox should s/^$/ /mgs before feeding stuff to `git patch-id'; and/or if `git patch-id' should be assuming empty lines and lines with a single SP are the same...

[1] https://public-inbox.org/meta/20220620192730.550803-3-e@80x24.org/