With recent setuptools, calling `python setup.py sdist` to create an
archive for zc.recipe.egg creates a zc_recipe_egg-xyz.zip instead of
a zc.recipe.egg-xyz.zip. This is called during test setup to prepare
a local package index, as the tests prevent access to PyPI. The name
change leads the index to find an entry for zc-recipe-egg instead of
zc.recipe.egg (as normalization replaces _ with -), which causes the
tests to fail to find a distribution for zc.recipe.egg.