For a long time now, tracing has been broken in Nixpkgs. So when you
have an eval error you would get something like this:

  error: while evaluating the attribute 'buildInputs' of the derivation 'hello-2.10' at /home/mbauer/nixpkgs/pkgs/stdenv/generic/make-derivation.nix:185:11:
  while evaluating 'chooseDevOutputs' at /home/mbauer/nixpkgs/lib/attrsets.nix:474:22, called from undefined position:
  while evaluating 'optionals' at /home/mbauer/nixpkgs/lib/lists.nix:257:5, called from /home/mbauer/nixpkgs/pkgs/stdenv/generic/make-derivation.nix:132:17:

This is coming from how Nix handles string context and how
make-derivation messes with the "name" attribute. This commit should
restore the old behavior so you get a nice line number like:

  error: while evaluating the attribute 'buildInputs' of the derivation 'hello-2.10' at /home/mbauer/nixpkgs/pkgs/applications/misc/hello/default.nix:4:3:
  while evaluating 'chooseDevOutputs' at /home/mbauer/nixpkgs/lib/attrsets.nix:474:22, called from undefined position:
  while evaluating 'optionals' at /home/mbauer/nixpkgs/lib/lists.nix:257:5, called from /home/mbauer/nixpkgs/pkgs/stdenv/generic/make-derivation.nix:132:17:

NOTE: This will still be broken for cross compilation due to the
prefixes we are adding to name.

We don’t want these to not even evaluate, otherwise we won’t know why
they’re broken. For now, I’ve left these as the latest version for a
default. In the future, maybe we should be smarter about choosing these.

sometimes this gets an infinite recursion error

This reverts commit 0307203.

cross should have higher precedence

make-derivation: fix position in trace