Mercurial: diffs in a particular changeset?
Solution 1:
Revision 2580 isn't necessasrily the parent revision of 2581. It's easy to check if it is, of course, but easier yet is to just do:
hg log -p -r 2581
That compares 2581 to its (first) parent revision no matter what it is, and most clearly encompasses the answer to the question "what the hell did 2581 do?"
Solution 2:
Try hg diff -r 2580 -r 2581.