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diff --git a/lib/python/Components/Element.py b/lib/python/Components/Element.py
index 54a1cc251cce6239537eec090249279db409d0d8..880274b423940ee761435d5c3ef964e45a21b55f 100644 (file)
--- a/lib/python/Components/Element.py
+++ b/lib/python/Components/Element.py
@@ -29,7 +29,9 @@ class Element:
                # we should not disconnect from upstream if
                # there are still elements depending on us.
                assert len(self.downstream_elements) == 0, "there are still downstream elements left"
-               if self.source:
+               
+               # Sources don't have a source themselves. don't do anything here.
+               if self.source is not None:
                        self.source.disconnectDownstream(self)
        
        def disconnectDownstream(self, downstream):