Thanks. I landed this now because IMO djgpp build is broken without it so I see no point in waiting until the next release.
I was not able to work with this PR the traditional way, it says it's from "unknown repository". Where is your curl fork?
For posterity I'll note found a workaround, that I'm sure to forget. I added .patch to the URL then git am'd it, like this
then I squashed all the commits into one via interactive rebase (so I could combine and edit all the commit messages), fetched upstream, rebased on upstream/master, checkout my master, merge --ff-only, review then push upstream.