We are migrating packages that meet below requirements:
1. using `callPackage`
2. called path is a directory
3. overriding set is empty (`{ }`)
4. not containing path expressions other than relative path (to
makenixpkgs-vet happy)
5. not referenced by nix files outside of the directory, other
than`pkgs/top-level/all-packages.nix`
6. not referencing nix files outside of the directory
7. not referencing `default.nix` (since it's changed to `package.nix`)
8. `outPath` doesn't change after migration
The tool is here: https://github.com/Aleksanaa/by-name-migrate.
I needed to use `git send-email`, and I wanted an MTA that
supported JMAP to use with it. We already package `mujmap`, but
even after bumping it to the latest Git commit to deal with Fastmail
authentication changes, it choked on the beautiful UTF‐8 email I
created. Enter this random Go tool from a random SourceHut repository
that did just the trick.