[Distutils] Version string normalization

[Jean-Paul Calderone]

Hello,

I've just noticed that when using setuptools, the name of the file created
by the sdist command changes.  The version passed to setup is "0.9.33+r17283"
but the file written is "Nevow-0.9.33-r17283.tar.gz".

This change causes various problems for me.  How can I avoid it?

Thanks,
Jean-Paul