[Python-Dev] Difference in RE between 3.2 and 3.3 (or Aaron Swartz memorial)

[MRAB]

On 2013-03-06 14:18, Amaury Forgeot d'Arc wrote:
> Hi,
>
> 2013/3/6 Matěj Cepl <mcepl at redhat.com <mailto:mcepl at redhat.com>>
>
>
>     On 2013-02-26, 16:25 GMT, Terry Reedy wrote:
>      > On 2/21/2013 4:22 PM, Matej Cepl wrote:
>      >> as my method to commemorate Aaron Swartz, I have decided to port his
>      >> html2text to work fully with the latest python 3.3. After some time
>      >> dealing with various bugs, I have now in my repo
>      >> https://github.com/mcepl/html2text (branch python3) working solution
>      >> which works all the way to python 3.2 (inclusive;
>      >> https://travis-ci.org/mcepl/html2text). However, the last problem
>      >> remains. This
>      >>
>      >> <li>Run this command:
>      >> <pre>ls -l *.html</pre></li>
>      >> <li>?</li>
>      >>
>      >> should lead to
>      >>
>      >>    * Run this command:
>      >>
>      >>          ls -l *.html
>      >>
>      >>    * ?
>      >>
>      >> but it doesn’t. It leads to this (with python 3.3 only)
>      >>
>      >>      * Run this command:
>      >>            ls -l *.html
>      >>
>      >>      * ?
>      >>
>      >> Does anybody know about something which changed in modules re or
>      >> http://docs.python.org/3.3/whatsnew/changelog.html between 3.2 and
>      >> 3.3, which could influence this script?
>      >
>      > Search the changelob or 3.3 misc/News for items affecting those two
>      > modules. There are at least 4.
>      > http://docs.python.org/3.3/whatsnew/changelog.html
>      >
>      > It is faintly possible that the switch from narrow/wide builds to
>      > unified builds somehow affected that. Have you tested with 2.7/3.2 on
>      > both narrow and wide unicode builds?
>
>     So, in the end, I have went the long way and bisected cpython to
>     find the commit which broke my tests, and it seems that the
>     culprit is http://hg.python.org/cpython/rev/123f2dc08b3e so it is
>     clearly something Unicode related.
>
>     Unfortunately, it really doesn't tell me what exactly is broken
>     (is it a known regression) and if there is known workaround.
>     Could anybody suggest a way how to find bugs on
>     http://bugs.python.org related to some particular commit (plain
>     search for 123f2dc0 didn’t find anything).
>
>
> I strongly suspect an incorrect usage of the "is" operator:
> https://github.com/mcepl/html2text/blob/master/html2text.py#L95
> Identity of strings is not guaranteed...
>
> Does it change something if you use "==" instead?
>
That function looks a little odd to me. Maybe I just don't understand
what it's doing! :-)