E306: False positive when preceded by 2 blank lines and a comment

[ryangalamb]

$ pycodestyle --version
2.7.0

If you have two blank lines, a comment, and then a nested function, E306 is raised erroneously.
(Since this false positive requires a genuine violation of E303, I don't think it's a big deal. But I noticed it, so I'm reporting it.)

The following functions both trigger false postives for E306.

def bad():
    _ = None


    # arbitrary comment

    def inner():  # E306 not expected (but happening! 1/2)
        pass

def bad():
    _ = None


    # arbitrary comment
    def inner():  # E306 not expected (but happening! 2/2)
        pass

For context, this snippet contains the false positives as well as cases that don't trigger E306:

def bad():
    _ = None


    # arbitrary comment

    def inner():  # E306 not expected (but happening! 1/2)
        pass


def bad():
    _ = None


    # arbitrary comment
    def inner():  # E306 not expected (but happening! 2/2)
        pass


def good():
    _ = None
    # arbitrary comment


    def inner():  # E306 not expected
        pass


def good():
    _ = None

    # arbitrary comment
    def inner():  # E306 not expected
        pass


def good():
    _ = None

    # arbitrary comment

    def inner():  # E306 not expected
        pass

If you dump that to a file (e.g., bug.py) and run pycodestyle on it, you'll get E306 inside the two bad() functions:

$ pycodestyle --select=E306 --show-source bug.py
bug.py:7:5: E306 expected 1 blank line before a nested definition, found 0
    def inner():  # E306 not expected (but happening! 1/2)
    ^
bug.py:16:5: E306 expected 1 blank line before a nested definition, found 0
    def inner():  # E306 not expected (but happening! 2/2)
    ^

Let me know if there's anything I can clarify/provide, thanks!