Don't import doctest globally; just import it in _test()
Don't import doctest globally; just import it in _test()

This improves load time because doctest is a large module. On my
machine, removing the global import of doctest decreases load time
from 60 ms to 30 ms.

Original author: Christophe Vu-Brugier <cvubrugier@yahoo.fr>

Datera/rtslib,Datera/rtslib,roidayan/rtslib,roidayan/rtslib