Splitting from T144780#2611657

In T144780#2611657, @Glaisher wrote:

In the case of https://meta.wikimedia.org/w/index.php?title=User_talk:MrLeopold&action=history, submission would have queued two jobs: one for a local talk page, another for the foreign talk page but the foreign wiki was selected by the user as Meta. See the _target link: in two messages, it's :metawikipedia:Template:Usurpation requested (foreign) and in the other two it's Template:Usurpation requested (local). This can be easily fixed in the code but the other issue is harder to debug without knowing the details of the error.

Then, as @Glaisher suggested, we should not allow to set "talk page on other wiki" being the same wiki as you're now.