Implicit requirement tempstorage

[dataflake]

The default generated Zope configuration contains a <zodb_db temporary> section, unless I specifically disable it with an empty zodb-temporary-storage setting.

Zope 4 does not come with tempstorage (or Products.TemporaryFolder) by default anymore, so this default configuration - at least for non-Plone installations - is broken.

I wonder if it would be possible to add some intelligent handling for the configuration generator. If zodb-temporary-storage is not explicitly set, it should look if tempstorage is in the generated list of eggs after all dependency resolution has happened, and only add the temporary database configuration then.

This is not a pressing issue for me, just a place where new (or even experienced users) will see unnecessary and unexpected breakage.