The split behavior here really looks like a bug. Limit "inheritance" is not documented, so it is a surprise for user.
UPD.: Thanks, choroba, somehow I missed that line :( . Now it seems normal behaviour. But in case '(split ... )[ ... ]' it doesn't look like DWIM, when split generates too few elements (which cant't be accessible by higher indexes which were used).
> when assigning to a list, if LIMIT is omitted (or zero), then LIMIT is treated as though it were one larger than the number of variables in the list;
then note that the quote was taken directly from the documentation of split.