As User:Rosenkohl rightfully points out, LogEventsList::showLogExtract is currently affected by dir=prev, probably much like the offset problem which was fixed in r56687.
See this for an example:
http://de.wikipedia.org/w/index.php?title=Spezial:Beitr%C3%A4ge&dir=prev&target=Angel54&uselang=en
The log snippet is from 8 May 2010, although the current block is from 17 May 2010.
Version: unspecified
Severity: enhancement