pkgutil._iter_file_finder_modules should not be fooled by *.py folders

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2017-03-09.11:46:10.278>
labels = ['3.7', 'type-bug', 'library']
title = 'pkgutil._iter_file_finder_modules should not be fooled by *.py folders'
updated_at = <Date 2017-03-10.02:04:13.571>
user = 'https://github.com/wm75'

bugs.python.org fields:

activity = <Date 2017-03-10.02:04:13.571>
actor = 'ncoghlan'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2017-03-09.11:46:10.278>
creator = 'wolma'
dependencies = []
files = ['46714']
hgrepos = []
issue_num = 29769
keywords = ['patch']
message_count = 2.0
messages = ['289285', '289333']
nosy_count = 3.0
nosy_names = ['ncoghlan', 'eric.snow', 'wolma']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue29769'
versions = ['Python 3.7']