Comment 9 for bug 581207

Right, I had indeed overlooked the issue. Thanks for your patience and the detailed explanation.
In this context, the complete patch makes sense indeed, and there are potentially other places in the code (i.e. other source files) that need patching as well. A quick grep on the trunk reveals the following places:

$ grep -rn --exclude="*.pyc" "lower()" *
softwarecenter/view/appview.py:272: k = os.environ["SOFTWARE_CENTER_SEARCHES_SORT_MODE"].strip().lower()
softwarecenter/view/historypane.py:225: search_matches = self.searchentry.get_text().lower() in pkg.lower()
softwarecenter/view/catview.py:231: q = xapian.Query("AC"+and_elem.text.lower())
softwarecenter/view/catview.py:240: xapian.Query("XS"+and_elem.text.lower()),
softwarecenter/view/catview.py:241: xapian.Query("AE"+and_elem.text.lower()))
softwarecenter/view/catview.py:245: q = xapian.Query("AT"+and_elem.text.lower())
softwarecenter/view/catview.py:249: q = xapian.Query("AH"+and_elem.text.lower())
softwarecenter/view/catview.py:254: q1 = xapian.Query("AP"+and_elem.text.lower())
softwarecenter/view/catview.py:256: xapian.Query("XP"+and_elem.text.lower()))
softwarecenter/view/catview.py:261: s = "pkg_wildcard:%s" % and_elem.text.lower()
softwarecenter/view/catview.py:278: return xapian.Query("AC"+include.text.lower())
softwarecenter/apt/apthistory.py:36: setattr(self, k.lower(), map(string.strip, sec[k].split(",")))
softwarecenter/apt/apthistory.py:38: setattr(self, k.lower(), [])
softwarecenter/apt/apthistory.py:42: count += len(getattr(self, k.lower()))
softwarecenter/db/update.py:130: if ignore.strip().lower() == "true":
softwarecenter/db/update.py:159: doc.add_term("AC"+cat.lower())
softwarecenter/db/update.py:163: doc.add_term("AT"+type.lower())
utils/installedapps.py:29: cmp=lambda x, y: cmp(x.split(":")[0].lower(),
utils/installedapps.py:30: y.split(":")[0].lower())))
utils/query.py:22: s = search_term.lower()
utils/query.py:33: query = xapian.Query(str_to_prefix[search_prefix]+search_term.lower())

How about putting the ascii_lower and ascii_upper functions in e.g. softwarecenter/utils.py and patching the whole codebase where relevant?