This was causing a few bits of suffering downstream, in particular, in
the NixOS module, which, after this change, can have the
`officialRelease` stuff in *it* completely deleted since we now have
correct defaulting in package.nix for it.
It also eliminates some automated editing of Nix files, which is
certainly always welcome to eliminate.
Fixes: https://git.lix.systems/lix-project/lix/issues/406
Change-Id: Id12f3018cff4633e379dbfcbe26b7bc84922bdaf
This commit constitutes the branch-off for 2.91. The parent of this
commit will be the branch point for release-2.90.
Change-Id: I7f047545df29a9cff93346137c865dcbf1415488
