bug#17373: 24.3.50; match data is incorrect if there are too many groups

[Drew Adams]

> Yes, unfortunately Emacs currently has a limit of at most 256 groups of
> match data: one for the entire pattern, and 255 for parenthesized
> subpatterns.  If you go over the limit, the excess matches are silently
> discarded.  I don't see this limitation documented anywhere; it should
> be.  Or better yet, the limitation should be removed.

Good to know.  +1, to documenting it, at least.