Copy Keyword does not work on Dynamic Arrays, only string

[Schmitty2005]

Program copyarr;

Type 

  Tar = Array Of Byte;

Var 
  a, b, c : Tar;
  x : Byte;
Begin
  setLength(a, 5);
  setLength(b, 5);

  For x := 0 To 4 Do
    Begin
      a[x] := x * x + 1;
      b[x] := x + 1;
    End;

  writeln(a[2]) ;
  c := copy(a, low(a), high(a));

  writeln(c[2]);
End.

Compiles and works in FPC

in Blaise :

$ ./blaise --source copyarr.pas --output arr
Semantic error: Type mismatch in assignment: expected 'array of Byte' but got 'string' at line 22 col 3 in copyarr