use offline-disutils in buildPythonPackage

pkgs/development/python-modules/generic/builder.sh

@@ -0,0 +1,10 @@
+source $stdenv/setup
+
+# do not allow distutils to make downloads, whatever install command is used
+export PYTHONPATH="${setuptools}/lib/${python.libPrefix}:$PYTHONPATH"
+export PYTHONPATH="${offlineDistutils}/lib/${python.libPrefix}:$PYTHONPATH"
+
+# enable pth files for dependencies
+export PYTHONPATH="${site}/lib/${python.libPrefix}/site-packages:$PYTHONPATH"
+
+genericBuild