zc.recipe.egg should support 'versions ='

zc.recipe.egg supports a "python =' setting, that allows choosing a different python executable for a script or interpreter with a set of eggs.

In a complex buildout that actually uses different pythons, it is very likely that one would also need different egg versions, so it should be possible to pass a "versions =" setting pointing to a possibly different section than the one specified on [buildout]