This is to fix issues with reverts being marked incorrectly,
especially when using the undoafter param which, until this patch,
wasn't really supported.
Honestly, EditPage is such a mess that I'm not sure if this is good
or not, but I did a lot of manual testing and it seems to work fine.
WikiPage::doEditContent() now checks whether the provided original
revision really has the same content as the new revision. This was
previously the task of callers, but that doesn't make much sense to
me because:
* This task would fall on EditPage otherwise and it should be more
focused on the UI side of things, without too much worrying about
backend details.
* This would require adding another parameter to WikiPage::
doEditContent(), $undoAfterId. It would be only useful for multiple-
revision undos that are not top revisions. In all other cases it
would be the same as $originalRevId.
* An extra sanity check before applying the value to the PageUpdater
won't hurt. Who knows what crazy ideas extensions might have.
The test cases are almost identical to those written for
McrUndoAction, so I decided to group them in a single file.
This should cover most undo cases.
Bug: T256915
Change-Id: I78641b3de0a012af932ea38265b695362f1f8491
5bf2cf380b