WIP: zc.recipe.egg: make 'interpreter' usable even when 'scripts' value is empty
This commit may be the wrong way, because recipes should never distinguish values between '' and None, simply because the buildout syntax has nothing to restore None when overriding. Which means that we should find something else to express "no script at all" or "default scripts".
A workaround is to put a dummy scripts value. The problem is that the recipe (and perhaps more generally zc.buildout.easy_install.scripts) should raise if a requested script can't be installed.