Description:
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Downloading a non-existant release gives HTTP 200 OK instead of 404 Not found

Reproduce code:
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e.g. http://pear.php.net/get/HTTP-1.3.0RC2.tgz
At the time of writing this that release doesn't exist. 

Expected result:
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However, the server answers with a HTTP-response-code of 200 (OK) and starts sending a zero-byte file.

Actual result:
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Maybe a 404 Not found could be returned instead?