More changes made to DigraphRemoveAllEdges

Author: rm387

gap/attr.gd

@@ -90,8 +90,7 @@ DeclareAttributeThatReturnsDigraph("DigraphReverse", IsDigraph);
 DeclareAttributeThatReturnsDigraph("DigraphDual", IsDigraph);
 DeclareAttributeThatReturnsDigraph("ReducedDigraph", IsDigraph);
 DeclareAttributeThatReturnsDigraph("DigraphRemoveAllMultipleEdges", IsDigraph);
-DeclareAttributeThatReturnsDigraph("DigraphRemoveAllEdges", IsImmutableDigraph);
-DeclareAttributeThatReturnsDigraph("DigraphRemoveAllEdges", IsMutableDigraph);
+DeclareAttributeThatReturnsDigraph("DigraphRemoveAllEdges", IsDigraph);
 
 # TODO replace all DeclareOperations below to
 # DeclareAttributeThatReturnsDigraph, and remove the *Attr versions.