There's an issue with the latest revision of pywikibot in pywikibot.showDiff, that wasn't there a few days ago (yesterday?). Easy to replicate:
```
import pywikibot
pywikibot.showDiff("test", "tast")
```
returns
```
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "pywikibot/__init__.py", line 681, in showDiff
PatchManager(oldtext, newtext, context=context).print_hunks()
File "pywikibot/tools/__init__.py", line 1327, in wrapper
return obj(*__args, **__kw)
File "pywikibot/diff.py", line 264, in __init__
hunk = Hunk(self.a, self.b, group)
File "pywikibot/diff.py", line 69, in __init__
self.diff_text = u''.join(self.format_diff())
File "pywikibot/diff.py", line 128, in format_diff
yield self.color_line(l1, l2)
File "pywikibot/diff.py", line 164, in color_line
char, self.colors[color])
File "pywikibot/tools/formatter.py", line 170, in color_format
return _ColorFormatter().format(text, *args, **kwargs)
File "/usr/lib/python2.7/string.py", line 545, in format
return self.vformat(format_string, args, kwargs)
File "pywikibot/tools/formatter.py", line 152, in vformat
kwargs)
File "/usr/lib/python2.7/string.py", line 549, in vformat
result = self._vformat(format_string, args, kwargs, used_args, 2)
File "pywikibot/tools/formatter.py", line 125, in _vformat
result = super(_ColorFormatter, self)._vformat(*args, **kwargs)
File "/usr/lib/python2.7/string.py", line 571, in _vformat
obj, arg_used = self.get_field(field_name, args, kwargs)
File "/usr/lib/python2.7/string.py", line 632, in get_field
obj = self.get_value(first, args, kwargs)
File "pywikibot/tools/formatter.py", line 82, in get_value
return super(_ColorFormatter, self).get_value(key, args, kwargs)
File "/usr/lib/python2.7/string.py", line 591, in get_value
return kwargs[key]
KeyError: u'color'
```