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

[eacousineau]

BPO	15768
Nosy	@ezio-melotti

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

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'

bugs.python.org fields:

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']

[eacousineau]

[Copying post I made here: http://stackoverflow.com/questions/12082886/bug-in-python-regex-re-sub-with-re-multiline]

I'm noticing some odd behavior in Python's Regex library, and I'm not sure if I'm doing something wrong.

If I run a regex on it using re.sub(), with re.MULTILINE. It seems to only replace the first few occurrences. It replaces all occurrences if I turn off re.MULTILINE, use re.subn(..., count = 0, flags = re.MULTILINE), or compile the regex using re.compile(..., re.MULTILINE).

I am running Python 2.7 on Ubuntu 12.04.

I've posted a random example on:

http://pastebin.com/49SU8Mm2 - Output from terminal
http://codepad.org/2RO2iS4O - Script, confirming behavior (except for re.subn(), which is different on 2.5)

[eacousineau]

Looks like I was just writing my code incorrectly - I should have been using re.sub(..., flags = re.MULTILINE).
That explains it.