BLD: do not propagate PYTHONPATH to scons commands.

Not needed as scons does not execute any Python jobs that would
need PYTHONPATH.

Author: pavoljuhas

SConstruct

@@ -27,8 +27,7 @@ def subdictionary(d, keyset):
 
 # copy system environment variables related to compilation
 DefaultEnvironment(ENV=subdictionary(os.environ, '''
-    PATH PYTHONPATH
-    CPATH CPLUS_INCLUDE_PATH LIBRARY_PATH LD_RUN_PATH
+    PATH CPATH CPLUS_INCLUDE_PATH LIBRARY_PATH LD_RUN_PATH
     LD_LIBRARY_PATH DYLD_LIBRARY_PATH DYLD_FALLBACK_LIBRARY_PATH
     MACOSX_DEPLOYMENT_TARGET
     '''.split())