Last modified: 2010-10-18 15:15:42 UTC
If you create a new skin that uses the ResourceLoader, the code adds in the contents of the page "MediaWiki:<skin name>.js" - but if that page is blank (as it would be by default), the string "<<skin name>.js>" shows up in the page, causing a Javascript error.
Retitling bug. The RL shouldn't add the message if it's empty.
Fixed in r74948.