Is there some way to ask Mercurial to show the revisions being diffed in the output? For example:

$ hg diff -r trunk:development
diff -r 08d51ecf22cf:ff5673e55b9f --git a/foo.c b/foo.c
...

Or something similar?

I've found that there have been a few times that I've taken a diff (eg, to review), but have later been unable to recreate it because I've forgotten which revisions it was taken against.