python-wrapper: recursively include all dependencies of the specified 'extraLibs' in the generated environment

This patch means that adding 'matplotlib' to extraLibs will automatically
include 'numpy', too, because matplotlib depends on it.

pkgs/development/interpreters/python/wrapper.nix

@@ -4,15 +4,17 @@
 
 (buildEnv {
   name = "python-${python.version}-wrapper";
-  paths = extraLibs ++ [ python makeWrapper recursivePthLoader ];
+  paths = stdenv.lib.filter (x : x ? pythonPath) (stdenv.lib.closePropagation extraLibs) ++ [ python recursivePthLoader ];
   ignoreCollisions = false;
 
   postBuild = ''
     . "${makeWrapper}/nix-support/setup-hook"
+
     if [ -L "$out/bin" ]; then
         unlink "$out/bin"
     fi
     mkdir -p "$out/bin"
+
     cd "${python}/bin"
     for prg in *; do
       echo "$prg --> $out/bin/$prg"