[PATCH] py3: use setattr() to assign new class attribute

[Yuya Nishihara]

On Tue, 24 May 2016 13:28:57 +0530, Pulkit Goyal wrote:
> > Out of curiosity, did you try simply not wrapping email.header.Header.__init__ on python 3? Based on the commentary in the docstring, it looks like it shouldn’t be required at all there.  
> 
> Yep I fixed that first and found this one, I send this one before though.

FYI, thanks to the refactoring of tests-patchbomb.t, 7f1d263a1bcb, tests
passed on Python 2.6.9 without this hack.