[Nix-dev] Removing nulls in BuildInputs

[roconnor at theorem.ca]

There was an idea tossed around on #nixos a few days ago that mkDerivation 
should remove the nulls from buildInputs (and maybe other items too). 
This would help make more consistent hashes that now currently change when 
we do refactoring that removes an item from the build input vs setting it 
to null.

I think this was a good idea, so I'm putting it forth here on nix-dev in 
the hopes that this feature request doesn't get lost.

Probably this patch would first go into stdenv-updates.

-- 
Russell O'Connor                                      <http://r6.ca/>
``All talk about `theft,''' the general counsel of the American Graphophone
Company wrote, ``is the merest claptrap, for there exists no property in
ideas musical, literary or artistic, except as defined by statute.''