F841 reports misleading location in try/except block

In this example pyflakes reports a misleading location for an unused variable:

$ cat example.py 
def foo():
    exc = None
    try:
        print('foo')
    except NameError as exc:
        print(exc)

$ pyflakes example.py 
example.py:5: local variable 'exc' is assigned to but never used

pyflakes reports exc on line 5 (the except line) as unused, which is misleading in my opinion since it's used within the exception handling. I guess that pyflakes recognizes that exc from line 2 (exc = None) as unused (which is unused actually), but determines line 5 as the last occuring declaration of exc.

Start by reproducing the report with the example.py snippet and the pyflakes command. Trace how the unused assignment and the except binding are associated with source locations. Done means the genuinely unused assignment is reported at its own line without falsely pointing to the except line when the exception variable is used.