code: def _scons_internal_warning(e):
      
      filename, lineno, routine, dummy = find_deepest_user_frame(traceback.extract_stack())
      sys.stderr.write("\nscons: warning: %s\n" % e.args[0])
      sys.stderr.write('File "%s", line %d, in %s\n' % (filename, lineno, routine))
docs: Slightly different from _scons_user_warning in that we use the
      *current call stack* rather than sys.exc_info() to get our stack trace.
      This is used by the warnings framework to print warnings.