Apparently, Special:UserRights allows to perform identical changes on user rights' if they happen in the space of a second.

You can see that at [1]; here's the log I can see at Special:UserRights for this user:

(change visibility) 2014-02-02T16:35:39 Odder (Talk | contribs | block) changed group membership for User:Marrovi from (none) to autopatroller (experienced contributor, no need to patrol their edits)
(change visibility) 2014-02-02T16:35:38 Odder (Talk | contribs | block) changed group membership for User:Marrovi from (none) to autopatroller (experienced contributor, no need to patrol their edits)

For one thing, the log shows incorrect change (the user has already been added to the 'autopatrolled' user group as of 2014-02-02T16:35:38), but it also should never have happened if the change was aimed at adding the user to a group they are already in.

Expected behaviour: (1) exit with an error message saying that the user is already in the expected user group and do not create an identical log entry for the second change.

References

• [1] https://commons.wikimedia.org/w/index.php?title=Special:Log&type=rights&page=User:Marrovi

Version: unspecified
Severity: normal