Wiki.Melancholie wrote:

Also happens if log-in at [[en:]] and log-out at [[de:]] for example (but not always, as it seems?)

charlie wrote:

Please note that this is only [[Help:Unified_login|unified login]], not [[en:Single Sign-on]]. This means that although you login to one project, you won't automatically be logged into all Wikimedia projects, and vice-versa. I'm not sure if Brion has plans to make this a Single Sign-on system or not.

Yes, that's already enabled... hence the bug report about inconsistencies with it. :)

This is a known, but mildly annoying issue.

Wiki.Melancholie wrote:

Mildly annoying?
The reason for a logout is for example the prevention from *account abuse by others* (in public, by brothers/sisters or friends); for example ;-)

The local wiki seems to give valid local login cookies. This is incorrect, only centralauth cookies should be valid for login.

Should be fixed in r35533, I'll close this bug when it goes live.