Python: drop python.majorVersion

Drop `python.majorVersion`. For Python language version, use `python.pythonVersion`.
For implementation version, use `python.sourceVersion`.

Some expressions were broken. Those that were identified were fixed.

fixup major

pkgs/development/interpreters/python/default.nix

@@ -39,8 +39,6 @@ with pkgs;
         pythonAtLeast = lib.versionAtLeast pythonVersion;
         pythonOlder = lib.versionOlder pythonVersion;
         inherit pythonForBuild;
-
-        majorVersion = pythonVersion; # Backwards compatibility. Should be dropped.
   };
 
 in {

pkgs/development/libraries/physics/geant4/g4py/default.nix

@@ -28,7 +28,7 @@ stdenv.mkDerivation rec {
   preConfigure = ''
     # Fix for boost 1.67+
     substituteInPlace CMakeLists.txt \
-    --replace "find_package(Boost)" "find_package(Boost 1.40 REQUIRED COMPONENTS python${builtins.replaceStrings ["."] [""] python.majorVersion})"
+    --replace "find_package(Boost)" "find_package(Boost 1.40 REQUIRED COMPONENTS python${builtins.replaceStrings ["."] [""] python.pythonVersion})"
     for f in `find . -name CMakeLists.txt`; do
       substituteInPlace "$f" \
         --replace "boost_python" "\''${Boost_LIBRARIES}"

pkgs/development/python-modules/tensorflow/bin.nix

@@ -45,7 +45,7 @@ in buildPythonPackage rec {
   format = "wheel";
 
   src = let
-    pyVerNoDot = lib.strings.stringAsChars (x: if x == "." then "" else x) "${python.majorVersion}";
+    pyVerNoDot = lib.strings.stringAsChars (x: if x == "." then "" else x) "${python.pythonVersion}";
     pyver = if stdenv.isDarwin then builtins.substring 0 1 pyVerNoDot else pyVerNoDot;
     platform = if stdenv.isDarwin then "mac" else "linux";
     unit = if cudaSupport then "gpu" else "cpu";