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I get duplicate text when inserting a link.

Steps to repro:

1. go to http://en.wikipedia.org/wiki/User:LuisVilla/sandbox
2. click "edit"
3. put cursor after "Public Works of Art Project"
4. hit enter
5. click the "link" icon in the toolbar
6. Type "Atmospheric river"
7. Hit enter twice (once to select, once to ... insert?)

Expected result:

Get the following markup:

[[Atmospheric river|Atmospheric river]]

Actual result:

[[Atmospheric river|Atmospheric riverAtmospheric river]]

The duplicated text is also visible in the Visual Editor, so it is an obvious/non-hidden bug.