inspect.getsource gets source copy on disk even when module has not been reloaded

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2016-04-30.03:33:07.191>
labels = ['library']
title = 'inspect.getsource gets source copy on disk even when module has not been reloaded'
updated_at = <Date 2017-02-21.16:37:00.426>
user = 'https://bugs.python.org/sebastienbourdeauducq'

bugs.python.org fields:

activity = <Date 2017-02-21.16:37:00.426>
actor = 'emilyemorehouse'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2016-04-30.03:33:07.191>
creator = 'sebastien.bourdeauducq'
dependencies = []
files = []
hgrepos = []
issue_num = 26890
keywords = []
message_count = 2.0
messages = ['264538', '264539']
nosy_count = 3.0
nosy_names = ['yselivanov', 'sebastien.bourdeauducq', 'emilyemorehouse']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue26890'
versions = ['Python 3.5']