In this answer, my link for ISS isn't getting rendered correctly.
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You somehow got a weird character appended to the end of your ISS link. Viewing the source:
: http://www.youtube.com/watch?v=MsHASky85cI [Chris Hadfield]: https://en.wikipedia.org/wiki/Chris_Hadfield [ISS]: http://en.wikipedia.org/wiki/International_Space_Station‎
The Markdown parser sees that left-to-right marker (
‎) and determines that your link is invalid and just doesn't render it.
Servy's edit didn't remove it either, just made it so that it was readable as a link: