Pywikibot faced some unicode issues in 2010-11 experienced with interwiki.py primarily.
This task is created to capture some of the history of that, as it is a key factor in some versions being listed as unsupported on the support matrix at https://www.mediawiki.org/wiki/Manual:Pywikibot/Version_table
[[http://bugs.python.org/issue10254 | Python issue 10254]] was initially raised as http://sourceforge.net/p/pywikipediabot/bugs/1246 , affecting Python 2.6.6, Python 2.7.0 and Python 3.0. The fix was merged into 2.6.7, Python 2.7.2, but was not backported into 2.7.1, and into Python 3 long before the lowest Pywikibot supported version of Python 3.3. Therefore this bug affects Pywikibot support on Python 2.6.6, Python 2.7.0 and Python 2.7.1.
http://sourceforge.net/p/pywikipediabot/bugs/1382/ was a related issue, apparently occurring in Python 2.6.5 ?, but the solution was "upgrade to 2.7.2", so there is little information about the cause or solution. It is listed as the reason that Python 2.5 was de-supported.