zfsUnstable: correct sha256

[hmenke]

Motivation for this change

The hash was not updated as part of #138168.

Also document the discussion from #136340 for the maintainers.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• 21.11 Release Notes (or backporting 21.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

[hmenke]

Result of nixpkgs-review pr 138427 run on x86_64-linux 1

2 packages marked as broken and skipped:

• linuxKernel.packages.linux_latest_libre.zfsUnstable
• linuxKernel.packages.linux_libre.zfsUnstable

18 packages built:

• linuxKernel.packages.linux_4_14.zfsUnstable
• linuxKernel.packages.linux_4_14_hardened.zfsUnstable
• linuxKernel.packages.linux_4_19.zfsUnstable
• linuxKernel.packages.linux_4_19_hardened.zfsUnstable
• linuxKernel.packages.linux_4_4.zfsUnstable
• linuxKernel.packages.linux_4_9.zfsUnstable
• linuxKernel.packages.linux_5_10.zfsUnstable
• linuxKernel.packages.linux_hardened.zfsUnstable (linuxKernel.packages.linux_5_10_hardened.zfsUnstable)
• linuxKernel.packages.linux_5_13.zfsUnstable
• linuxKernel.packages.linux_5_13_hardened.zfsUnstable
• linuxKernel.packages.linux_5_14.zfsUnstable
• linuxKernel.packages.linux_5_4.zfsUnstable
• linuxKernel.packages.linux_5_4_hardened.zfsUnstable
• linuxKernel.packages.linux_lqx.zfsUnstable
• linuxKernel.packages.linux_testing_bcachefs.zfsUnstable
• linuxKernel.packages.linux_xanmod.zfsUnstable
• linuxKernel.packages.linux_zen.zfsUnstable
• zfsUnstable

[hmenke]

Oops, ofborg fails with No space left on device

[Mic92]

Works for me.