non-ascii changed line causes diff to crash

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A non-ascii changed line causes fragments diff to crash with:

Traceback (most recent call last):
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/runpy.py", line 162, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/Users/matt/local/src/fragments/fragments/__main__.py", line 8, in <module>
    _main()
  File "/Users/matt/local/src/fragments/fragments/commands.py", line 412, in _main
    print(str(l))
  File "/Users/matt/local/src/fragments/fragments/color.py", line 25, in __str__
    return '\033[%sm\033[%sm%s\033[0m' % (self.weight, self.color, super(ColoredString, self).__str__())
UnicodeEncodeError: 'ascii' codec can't encode character u'\xb4' in position 35: ordinal not in range(128)