Make == be aware of end-elliptic lists (from gforge #20284)
Imported issue: Initially reported by @chevilla in https://gforge.inria.fr/tracker/?group_id=1015&aid=20284
Sollya is currently not able to recognize as equal two end-elliptic lists when they are not structurally equal.
Example:
L1 = [|1,2...|]; L2 = [|1,2...|]; L1 == L2;
returns true, but
L1 = [|1,2...|]; L2 = [|1,2,3...|]; L1 == L2;
returns false, even though both lists have exactly the same elements.
It would be more coherent if they were recognized as equal. Of course, it seems reasonable to keep deciding that they are not structurally equal, and it is not a problem that their hash values be different (actually, it would be complicated to ensure equality of hashes for all end-elliptic lists that are equal to a given list).