See merge request !1914

An unicode encoding error was being raised in
test_AccountingTransaction_getListBoxColumnList_item_column in Python 2,
when the `html` variable was being passed to the `StringIO`
constructor. The error was only reproducible when running the tests in
the CLI.

The problem was that we were using cStringIO module in Python 2, and the
string فارسی (farsi) appears in the HTML (probably inside a language
picker). cStringIO cannot parse unicode characters that are non-ASCII.
The solution is to use "six.StringIO", which uses the (slower,
but unicode-compatible) StringIO module in Python 2.

( I'm wondering if we need this patch at all on py3 )

__getitem__ was missing causing unsubscriptable-object on BTrees

fixup! fixup! fixup! fixup! fixup! XMLExportImport: more support pickle protocol 3 🚧 ( repair python2 )

This is no longer needed now, maybe since Zope4 or maybe since a patch
in slapos. This option does not exist on python3 and using pylint on
python3 complains about these disable, so we have to remove them on
python2 as well.