[BUG] debug.getlocal does not pick up vararg

[Dirk Laurie <dirk.laurie@...>]

The following behaviour appears for the first time in Lua 5.3.2:

> function f(a,b,...)
>> for k=-2,4 do print(k,debug.getlocal(1,k)) end end
> f(1,2,-1,-2,-2)
-2    nil
-1    nil
0    nil
1    a    1
2    b    2
3    (for index)    3
4    (for limit)    4

It is still present in Lua 5.3.3.