Author: FT2.wiki
Description:
If a revision did not have an edit summary, then the word "[deleted]" can be placed exactly where the edit summary would normally go. It therefore appears to be showing an edit summary was deleted, whereas in fact no edit summary ever existed.
Example: http://en.wikipedia.org/w/index.php?title=Special:RevisionDelete&oldid=284084867 (visible to oversighters only)
To reproduce - create a revision with blank edit summary, then RevDelete it using "Delete revision text" as the only selected option. The result looks like this:
(diff) <s>date</s> username [deleted]
Version: unspecified
Severity: minor