Last modified: 2008-01-16 07:16:11 UTC
This is, in theory, a security bug (allowing users to perform actions that are outside their permissions), but is actually minor because the action is so pointless. If a page whose name contains a space is a redirect to itself, and only has one entry in the history, it's possible for a non-administrator (specifically, someone without the 'delete' right) to move a page with the same name but with a non-breaking space in the title over the page with a space in the title; the software apparently confuses this with the reverse-a-redirect case where a page is moved over a redirect that points to the page being moved. The redirect-to-self is completely obliterated, leaving no deletion log entry nor deleted history. It seems unlikely that this is intended behaviour, although it is likely to be harmless.
I daresay this is an unintended feature: pages with in their titles shouldn't exist, nor should redirects to self.
This isn't an -related issue at all -- you can move over *any* self-redirect with no history.
This appears to actually be on purpose... in Title::isValidMoveTarget() you'll find:
# Does the redirect point to the source?
# Or is it a broken self-redirect, usually caused by namespace collisions?
So... not a bug, intended behavior. :)