If you head to a deleted revision with enough rights (example on BC), a message is shown asking if you want to actually view the diff. Clicking the link shows the diff as promised, but not the page text (example). It didn't use to work like this, and you would normally see the actual page text. I guess this is some sort of regression, but I haven't found what caused it.
Also, the same thing happens without diffs. Opening the page of a deleted revision (ex) and clicking "view this revision" results in an empty page.

On my wiki, where I have MediaWiki master from August 28th, this doesn't happen.