I discovered this problem while migrating a page from Wikimedia which uses two square brackets for links instead of one. Narrowed the bug down to the following. Start with this:

[one]
[two]

Edit both links names such as this:

[one1]
[two2]

Revision history has two problems:

1) The revision of the second link doesn't even appear on the history page – it's like it disappeared
2) The revision of the first link is displayed as a deleted line when it should show as a word change (add more text around each link to see this behavior)

Possibly unrelated, but on the page Info tag, the latest revision is not displayed in the Recent Changes box. I have to click on "View page history" and manual compare the last two version to see the latest revision.