Using flake8-string-format I can see several problems with Python 2.6.
$ flake8 . | grep ': P'
./pycolorname/color_system.py:86:30: P101 format string does contain unindexed parameters
./pycolorname/pantone/cal_print.py:58:18: P101 format string does contain unindexed parameters
./pycolorname/pantone/pantonepaint.py:29:22: P103 other string does contain unindexed parameters
./pycolorname/ral/classic/ralcolor.py:41:24: P101 format string does contain unindexed parameters
./pycolorname/ral/classic/wikipedia.py:30:20: P101 format string does contain unindexed parameters
Pywikibot supports Python 2.6.
Using
flake8-string-format
I can see several problems with Python 2.6.