re.sub() with re.MULTILINE not replacing all occurrences #59972

assignee = None
closed_at = <Date 2012-08-23.00:05:02.788>
created_at = <Date 2012-08-23.00:03:04.857>
labels = ['expert-regex', 'type-bug', 'invalid']
title = 're.sub() with re.MULTILINE not replacing all occurrences'
updated_at = <Date 2012-08-23.00:05:02.786>
user = 'https://bugs.python.org/eacousineau'

activity = <Date 2012-08-23.00:05:02.786>
actor = 'eacousineau'
assignee = 'none'
closed = True
closed_date = <Date 2012-08-23.00:05:02.788>
closer = 'eacousineau'
components = ['Regular Expressions']
creation = <Date 2012-08-23.00:03:04.857>
creator = 'eacousineau'
dependencies = []
files = []
hgrepos = []
issue_num = 15768
keywords = []
message_count = 2.0
messages = ['168909', '168910']
nosy_count = 3.0
nosy_names = ['ezio.melotti', 'mrabarnett', 'eacousineau']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = None
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue15768'
versions = ['Python 2.7']