Handle non ascii in response class __str__

[johanlundberg]

I was apparently confused in my last PR (#550) when I tried to fix the response class __str__.

This should (hopefully) be the correct way of handling a response string containing non ascii characters.

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[c00kiemon5ter]

I have filled issue #2902 with PyPy3 for the failing build.

[c00kiemon5ter]

self.xmlstr should always be a str. str(self.xmlstr) will always result to the same value as self.xmlstr. str(...) shouldn't be needed here.

[johanlundberg]

I agree, but is it a should or would ;). I will update my PR as I can't find any way for self.xmlstr to be anything other than a string as you say.

[johanlundberg]

We where not quite right as self.xmlstr can be bytes when using Python 3.x. The test that was failing was test_flow in test_65_authn_query.

[c00kiemon5ter]

I merged this, ignoring the failing case for pypy3. There is nothing we can do about it. It is up to travis-ci to update their image and upgrade pypy3 to a stable version. For reference Python 3.5.3[pypy-6.0.0-final] works fine.

As for the PR itself, I opted to store xmlstr in the correct type when it is initialized. That way there is no need to check again what should be done.

[johanlundberg]

Sounds good. Thank you!