Non ASCII characters raise errors when comparing versions of a document

[danielhz]

I create a news item that use plone.app.contenttypes 1.1b5 in Plone 4.3.6. If I include non ASCII characters in the news item body, then it fails when trying to compare versions in the history. I used this buildout.

Note: I have previously submitted this issue in plone.app.contenttypes but @pbauer said me that this could be a CMFDiffTool issue. I'm not sure if this is the place to submit this issue.