Group inclusion tests is broken when interacting with list list matrices and compressed matrices. #6672

gap> G := Group( [ [ 1, 1 ], [ 0, 1 ] ] * Z(2), [ [ 0, 1 ], [ 1, 0 ] ] * Z(2) );
Group([ <an immutable 2x2 matrix over GF2>, <an immutable 2x2 matrix over GF2> ])
gap> y := [ [ 1, 0 ], [ 1, 1 ] ] * Z(2);
[ [ Z(2)^0, 0*Z(2) ], [ Z(2)^0, Z(2)^0 ] ]
gap> x := ImmutableMatrix( GF(4), y );
[ [ Z(2)^0, 0*Z(2) ], [ Z(2)^0, Z(2)^0 ] ]
gap> x = y;
true
gap> y in G;
true
gap> x in G;
false
gap> Is8BitMatrixRep( x );
true
gap> Is8BitMatrixRep( y );
false