It appears I just had to be patient! The place where it says “Fix Commit” on that page eventually changed into a link to the commit on Github.
However, I think there might be something wrong with the commit – it references a file called “NiagaraShaderParametersBuilder.h” which might not have gotten committed, because I see no sign of it anywhere on the Github. It was only moved to release branch yesterday and I’m guessing it might have broken the build, so I’m guessing I just need to wait.