Add flag to disable PYTHONNOUSERSITE for wrapped python binaries

pkgs/development/interpreters/python/mk-python-derivation.nix

@@ -46,6 +46,9 @@
 # Skip wrapping of python programs altogether
 , dontWrapPythonPrograms ? false
 
+# Skip setting the PYTHONNOUSERSITE environment variable in wrapped programs
+, skipNoUserSite ? false
+
 # Remove bytecode from bin folder.
 # When a Python script has the extension `.py`, bytecode is generated
 # Typically, executables in bin have no extension, so no bytecode is generated.
@@ -93,6 +96,7 @@ let self = toPythonModule (python.stdenv.mkDerivation (builtins.removeAttrs attr
   installCheckInputs = checkInputs;
 
   postFixup = lib.optionalString (!dontWrapPythonPrograms) ''
+    ${if skipNoUserSite then "export SKIPNOUSERSITE=1" else ""}
     wrapPythonPrograms
   '' + lib.optionalString removeBinBytecode ''
     if [ -d "$out/bin" ]; then