'' is not in tuple

slapos/recipe/downloadunpacked.py

@@ -48,7 +48,7 @@ class Recipe:
           'exclusive.')
     self.parts = None
     self.destination = self.options.get('destination', None)
-    self.shared = shared = is_true(options.get('shared', '').lower())
+    self.shared = shared = is_true(options.get('shared', 'false').lower())
     if self.destination is None:
       if shared:
         shared_part = buildout['buildout'].get('shared-part', None)