global/local syntax errors not caught

This is perhaps a bit obscure, but here's a class of syntax errors that aren't caught by pyflakes

$ cat test.py
def test(x):
    global x
$ pyflakes test.py
$ python test.py
  File "test.py", line 2
    global x
SyntaxError: name 'x' is parameter and global

I'm unsure what the full set of possible errors are here. One would need to check the Python source. I know there are some others relating to the Python 3 "nonlocal" keyword as well.