If you patrol a revision via RevisionReview, but your session is invalid (for example if you delete your token), you get a page that displays MediaWiki:Sessionfailure. So far so good, but the headline is MediaWiki:Markedaspatrolled which says that revision-marking was successful (which is not the case). Example:

http://de.wikipedia.org/w/index.php?title=Spezial:RevisionReview&patrolonly=1&target=Kategorie:Instandhaltung&rcid=45953177&token=

Version: unspecified
Severity: minor