mimetypes libmagic compatibility

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2018-08-05.16:48:48.342>
labels = ['extension-modules', 'type-feature']
title = 'mimetypes libmagic compatibility'
updated_at = <Date 2018-08-05.16:48:48.342>
user = 'https://bugs.python.org/bpypy'

bugs.python.org fields:

activity = <Date 2018-08-05.16:48:48.342>
actor = 'bpypy'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Extension Modules']
creation = <Date 2018-08-05.16:48:48.342>
creator = 'bpypy'
dependencies = []
files = []
hgrepos = []
issue_num = 34340
keywords = []
message_count = 1.0
messages = ['323160']
nosy_count = 1.0
nosy_names = ['bpypy']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue34340'
versions = []