This was a very recent change (i.e., adding the display of the diff below the rollback). However, I should note that this is somewhat of a wretched zinger when using rollback on, for example, huge vandal revisions (e.g., those 1mb vandalisms) that freeze up the browser by looking at the diff.
Anyway, I figure it would be easy and overall better if it was individually able to be enabled or disabled by people performing rollbacks.
Cheers. =)
-slakr@enwiki
Version: 1.14.x
Severity: normal