Here is a patch that properly raises SyntaxError when 'return' or  
'yield' statements appear outside a function.

I did not bother to update the (deprecated) compiler package: it seems 
to be completely foreign to this kind of checks...

>>> dis.dis(compiler.compile("return 1", "module.py", "exec"))
  1           0 LOAD_CONST               1 (1)
              3 RETURN_VALUE
              4 LOAD_CONST               0 (None)
              7 RETURN_VALUE