* Parser generates signature to compare against
* Signature can be overwritten per wiki, in NS_MEDIAWIKI
* Such overwritten default can be different depending on
page the signature is on[1]
* Our comparison signature generation was page-agnostic
(always from Title::newMainPage)
* Signatures didn't match up on own talk pages, where
default signature is different
Also added 2 new tests cases & improved tests by also
setting the page
1: https://en.wikipedia.org/w/index.php?title=MediaWiki%3ASignature&diff=176507985&oldid=176229132
Bug: T78424
Change-Id: Ice151d4d16236a5d1556ef62805b61310c7beb85
