In the Regular Expression HOWTO
https://docs.python.org/3.6/howto/regex.html#regex-howto
the last example in the "Grouping" section has a bug. The code is supposed to find repeated words, but it catches false repetitions.

>>> p = re.compile(r'(\b\w+)\s+\1')
>>> p.search('Paris in the the spring').group()
'the the'
>>> p.search('k is the thermal coefficient').group()
'the the'

I propose adding a \b after \1, this solves the problem :

>>> p = re.compile(r'(\b\w+)\s+\1\b')
>>> p.search('Paris in the the spring').group()
'the the'
>>> print p.search('k is the thermal coefficient')
None

Just discovered that a nearly identical example is presented in the end of section "Non-capturing and Named Groups". My proposal applies to this other example, too.
And, by the way, reading this HOWTO has been very useful to me.

Looks like both examples need a closing \b. Is this being worked on or should I submit a PR?

This topic seems stuck. Is there anything else I should do ?

Do you mind to create a pull request on GitHub Cristian?

I'm sorry, I have no experience at all with Git. Could you please do it for me ?
The bug appears in two places, see my first two messages.
Thank you

Serhiy, Christian: I'll submit a PR for this later today.

Cristian, Serhiy: I've submitted a PR for this bug. 

Cristian: I apologize for misspelling your name in a prior post.

New changeset 610e5afdcbe3eca906ef32f4e0364e20e1b1ad23 by Mariatta (Mandeep Bhutani) in branch 'master':
bpo-30004: Fix the code example of using group in Regex Howto Docs (GH-4443)
https://github.com/python/cpython/commit/610e5afdcbe3eca906ef32f4e0364e20e1b1ad23

New changeset c02037d62284f4d4ca6b22f2ed05165ce2014951 by Mariatta (Miss Islington (bot)) in branch '2.7':
bpo-30004: Fix the code example of using group in Regex Howto Docs (GH-4443) (GH-4555)
https://github.com/python/cpython/commit/c02037d62284f4d4ca6b22f2ed05165ce2014951

New changeset 3e60747025edc34b503397ab8211be59cfdd05cd by Mariatta (Miss Islington (bot)) in branch '3.6':
bpo-30004: Fix the code example of using group in Regex Howto Docs (GH-4443) (GH-4554)
https://github.com/python/cpython/commit/3e60747025edc34b503397ab8211be59cfdd05cd

Thanks everyone. I merged the PR, and it's been backported to 3.6 and 2.7

Thank you Cristian for reporting this issue. Thank you Mandeep for your patch. Thank you Mariatta for merging.