Cardinality of sets prints unexpected value

[gradha]

With the following example:

type
  SquareIndex* = range[0..63]
  Bitboard* = set[SquareIndex]

proc test() =
  const values = [3, 47, 48, 54, 53, 63]
  var b: Bitboard
  for f in values:
    echo "Card: ", b.card
    b.incl(f)
    echo "Added ", f

  for f in 0..high(SquareIndex):
    if f in b:
      echo "Value ", f, " found in bitboard"

when isMainModule: test()

Compiled with Nim 0.11.2 under OSX shows the following output:

Card: 0
Added 3
Card: 1
Added 47
Card: 2
Added 48
Card: 2
Added 54
Card: 2
Added 53
Card: 2
Added 63
Value 3 found in bitboard
Value 47 found in bitboard
Value 48 found in bitboard
Value 53 found in bitboard
Value 54 found in bitboard
Value 63 found in bitboard

The cardinality doesn't increase for set values greater than 47. The expected result was to have a final cardinality of six.

[Araq]

Pretty sure this works on devel.