sscanf return value with %*-assignments

[thekid]

HHVM Version

3.20.2

Standalone code, or other way to reproduce the problem

$ echo '<?php var_dump([sscanf("C:", "%c%*[:]", $drive), $drive]);' | hhvm --php /dev/stdin

Expected result

array(2) {
  [0]=>
  int(2)
  [1]=>
  string(1) "C"
}

Actual result

array(2) {
  [0]=>
  int(1)
  [1]=>
  string(1) "C"
}