Also from that thread, the only way to fix it is to use a version of Nix <= 2.3. Based on the specifics of the problem I’d guess you might be able to install it declaratively in your config files, but I haven’t tested it.
I suggest you report that problem to the creator of that search tool since every nix-shell invocation they give for nixpkgs older than 19.09 will fail with any Nix > 2.3. I don’t think there exists official Nix documentation with those instructions otherwise we’d need to update it there as well.
Thanks for the reply. Appreciated.
Curiously NIx 2.10.2 has just been released, installed it
just after posting this issue and the problem no longer exists.
I now have two versions of vim installed using nix-shell vim 8.0.442
and 8.1.578. Not bad at all for a vanilla Debian stable distro.
Only issue now is how to have each version of vim have it’s own dot
file settings. Probably not possible I suspect.
Thanks again
Murray