Updated mediawiki/extensions
Project: mediawiki/extensions/Scribunto  99b96d8b1451fa77f01fd3b1f754831ebcca42f3

Add frontier pattern (%f[set]) to ustring

The "%f[set]" frontier pattern has been in Lua 5.1 since the beginning,
but was undocumented until Lua 5.2. And the code is even unchanged from
5.1.0 to 5.2.1. So there's no reason not to implement it in ustring too.

Note the changes to UstringLibrary.php are somewhat large, because it
splits the "convert a Lua bracketed charset to PCRE" code into a
separate function and it changes the handling of mw.ustring.find's and
mw.ustring.match's 'init' parameter from "substring, match from 0, then
add back on $init" to "use preg_match's $offset and use \G instead of ^
where this matters". Both of these are necessary to properly support
%f.

This also fixes a bug in the pure-Lua code (not used in Scribunto)
exposed by the unit tests for %f where %z was matching '\1' rather than
'\0' and %Z everything except '\1' instead of everything except '\0'.

Bug: 48331
Change-Id: Ie0b95ef5b734db53d6adc9de5dae4874f8944c08