nixpkgs: remove redundant attribute sip

Because:

 1. It is a mere alias of `pythonPackages.sip`
 2. It is usually not needed since propagated by `pyqt4`
 3. It makes it easy to have a packages depend on two different versions
 of sip

pkgs/applications/gis/qgis/default.nix

@@ -1,10 +1,10 @@
 { stdenv, fetchurl, gdal, cmake, qt4, flex, bison, proj, geos, x11, sqlite, gsl,
-  pyqt4, qwt, fcgi, python, libspatialindex, libspatialite, sip }:
+  pyqt4, qwt, fcgi, python, libspatialindex, libspatialite }:
 
 stdenv.mkDerivation rec {
   name = "qgis-2.4.0";
 
-  buildInputs = [ gdal qt4 flex bison proj geos x11 sqlite gsl pyqt4 sip qwt
+  buildInputs = [ gdal qt4 flex bison proj geos x11 sqlite gsl pyqt4 qwt
     fcgi libspatialindex libspatialite ];
 
   nativeBuildInputs = [ cmake python ];

pkgs/desktops/kde-4.14/applications/kate.nix

@@ -1,8 +1,8 @@
-{ stdenv, kde, kdelibs, kactivities, qjson, pyqt4, sip, python, pykde4}:
+{ stdenv, kde, kdelibs, kactivities, qjson, pyqt4, python, pykde4}:
 
 kde {
 
-  buildInputs = [ kdelibs kactivities qjson pyqt4 sip python pykde4 ];
+  buildInputs = [ kdelibs kactivities qjson pyqt4 python pykde4 ];
 
   meta = {
     description = "Kate, the KDE Advanced Text Editor, as well as KWrite";

pkgs/desktops/kde-4.14/kdebindings/pykde4.nix

@@ -1,4 +1,4 @@
-{ kde, kdelibs, python, sip, pyqt4, kdepimlibs, shared_desktop_ontologies,
+{ kde, kdelibs, python, pyqt4, kdepimlibs, shared_desktop_ontologies,
   polkit_qt4, boost, lndir, pkgconfig }:
 
 let pydir = "lib/python${python.majorVersion}"; in
@@ -14,7 +14,7 @@ kde {
 
   nativeBuildInputs = [ pkgconfig ];
 
-  propagatedBuildInputs = [ pyqt4 sip ];
+  propagatedBuildInputs = [ pyqt4 ];
 
   preConfigure =
     ''

pkgs/development/python-modules/pyqt/4.x.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, python, sip, qt4, pythonDBus, pkgconfig, lndir, makeWrapper }:
+{ stdenv, fetchurl, python, pythonPackages, qt4, pythonDBus, pkgconfig, lndir, makeWrapper }:
 
 let version = "4.10.2"; # kde410.pykde4 doesn't build with 4.10.3
 in
@@ -30,7 +30,7 @@ stdenv.mkDerivation {
 
   buildInputs = [ python pkgconfig makeWrapper qt4 lndir ];
 
-  propagatedBuildInputs = [ sip ];
+  propagatedBuildInputs = [ pythonPackages.sip ];
 
   postInstall = ''
     for i in $out/bin/*; do

pkgs/shells/ipython/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, buildPythonPackage, pythonPackages, pyqt4 ? null, sip ? null
+{ stdenv, fetchurl, buildPythonPackage, pythonPackages, pyqt4 ? null
 , notebookSupport ? true   # ipython notebook
 , qtconsoleSupport ? true  # ipython qtconsole
 , pylabSupport ? true      # ipython --pylab    (backend: agg - no gui, just file)
@@ -10,7 +10,7 @@
 # pyqt4 for both.
 
 assert qtconsoleSupport == true -> pyqt4 != null;
-assert pylabQtSupport == true -> pyqt4 != null && sip != null;
+assert pylabQtSupport == true -> pyqt4 != null;
 
 buildPythonPackage rec {
   name = "ipython-2.3.1";
@@ -37,7 +37,6 @@ buildPythonPackage rec {
   ] ++ stdenv.lib.optionals pylabQtSupport [
     pythonPackages.matplotlib
     pyqt4
-    sip
   ];
 
   doCheck = false;

pkgs/top-level/all-packages.nix

@@ -7448,8 +7448,6 @@ let
 
   rhpl = callPackage ../development/python-modules/rhpl { };
 
-  sip = pythonPackages.sip;
-
   pyqt4 = callPackage ../development/python-modules/pyqt/4.x.nix {
     stdenv = if stdenv.isDarwin
       then clangStdenv

pkgs/top-level/python-packages.nix

@@ -144,6 +144,7 @@ let
 
   pyqt4 = callPackage ../development/python-modules/pyqt/4.x.nix {
     pythonDBus = self.dbus;
+    pythonPackages = self;
   };
 
   pyqt5 = callPackage ../development/python-modules/pyqt/5.x.nix {
@@ -2911,7 +2912,7 @@ let
       md5 = "9c4c5a59b878aed78e96a6ae58c6c185";
     };
 
-    propagatedBuildInputs = [ pkgs.pyqt4 pkgs.sip pkgs.pkgconfig pkgs.popplerQt4 ];
+    propagatedBuildInputs = [ pkgs.pyqt4 pkgs.pkgconfig pkgs.popplerQt4 ];
 
     preBuild = "${python}/bin/${python.executable} setup.py build_ext" +
                " --include-dirs=${pkgs.popplerQt4}/include/poppler/";