nix flake

[tcoopman]

The flake to run scm-diff-editor at git-branchless currently fails with scm-record no such file or directory.
I took me a while to figure out that this was extracted.

Could a flake be provided for scm-record as well, so that I can install scm-diff-editor via nix?

[arxanas]

I don't know anything about Nix (and didn't write the original flake) so someone else would have to provide the fix.