composer/composer — pull request #1485 by halk (2013-01-14 17:45:03+00:00)
Title: Fixed chmod for binary link in unixy proxy envs

This should solve issue #1270

I was only able to reproduce that issue on the same environment as the issuer mentioned, meaning Koding.com. It looks like that environment triggers generateUnixyProxyCode(). As that method is called, file at $link might not exist, therefore chmod there does not make sense.