Otherwise references to the Python interpreter inside the set are wrong, as demonstrated by:
``` nix
with import <nixpkgs> { };
let
python' = python3.override {
packageOverrides = final: prev: { requests = prev.requests.overridePythonAttrs(old: { version = "1337"; }); };
};
in python'.pkgs.python.pkgs.requests
```
which returns the _non_ overriden requests.
And the same with `self`:
```
with import <nixpkgs> { };
let
python' = python3.override {
self = python';
packageOverrides = final: prev: { requests = prev.requests.overridePythonAttrs(old: { version = "1337"; }); };
};
in python'.pkgs.python.pkgs.requests
```
which returns the overriden requests.
This can manifest itself as file collisions when constructing environments or as subtly incorrect dependency graphs.
checkInputs used to be added to nativeBuildInputs. Now we have
nativeCheckInputs to do that instead. Doing this treewide change allows
to keep hashes identical to before the introduction of
nativeCheckInputs.
