These dependencies need to be pulled from the same unstable commit that
cabal2nix is pulled from, otherwise changes to any of them will not be
in effect and possibly break the build.
(cherry picked from commit 631661e66c)
The contribution guidelines require an unstable version to be leading
with a real version, or if none is available with `0-`.
This is because certain Nix operations split a package's full name into
name and version component starting with the first section starting with
a digit.
(cherry picked from commit 453d0f8eab)
Based on the Nixpkgs used and the version of nixfmt-rfc-style in that
version, it's likely that not the correct version is used.
Update scripts should instead run within a Nixpkgs development shell
(`nix-shell`/`nix develop`/`direnv`), where the correct version of
`nixfmt` (although `treefmt` should be preferred) is always available.
