Currently when trying to edit and entity and give it a sitelink that is already used on another entity the messages in the error are returned such as below.

[name] => wikibase-error-sitelink-already-used
[type] => error
[parameters] => Array(

 [0] => //de.wikipedia.org/wiki/Sacha_Baron_Cohen
 [1] => Sacha Baron Cohen
 [2] => Q29055
)

This gives the full url, title and entity.
It would make a lot of sense to also have another parameter of the siteid!!!

Version: master
Severity: enhancement