zope: force module import by importing symbols Previously, we tried to import a module and handle the ImportError. Our lazy module importer doesn't verify the module exists and returns a dummy object representing the module. Only once we attempt to load a symbol in the module does the ImportError get raises. This means that simple imports inside `try..except ImportError` don't detect missing modules. This commit changes imports in zope.interface to access symbols, thus forcing module load and triggering ImportError. This fixes zope.interface for pure builds. Differential Revision: https://phab.mercurial-scm.org/D2980