Last modified: 2012-04-08 21:09:03 UTC
I'm going to assume that the ". ." separator between the (+/-xx) is to separate it from the edit summary to the right of it; if so, then this needs to not appear when there isn't an edit summary.
Example: http://en.wikipedia.org/w/index.php?title=Cat&offset=20120117144701&limit=1&action=history
https://gerrit.wikimedia.org/r/4551