Forums Bug Reports (n1 isnum n2-) always matches $true condition

alias isnumtest {
  if (1 isnum 3-) echo -a *fail $v1 isnum $v2
  else echo -a *ok $v1 !isnum $v2
  if (1 isnum 3-9) echo -a *fail $v1 isnum $v2
  else echo -a *ok $v1 !isnum $v2
}