This bug might belong in the URL-related section.
I believe it to be a generic problem.

If you fopen() an URL
that returns with an HTTP Header of NoContent (204),
fopen() will fail with Error 0.

Failure would be ok if there was a specific error
code for NoContent URLs.  Either that or returning
a handle that was already at eof would suffice.
As it is now, there's no way to tell the difference
between a bad (NotFound) URL and a NoContent URL.

Work-around it to use cURL to a temporary file
and check the HTTP_CODE with the undocumented
curl_getinfo() function.  Of course, it seems
a little weird to require the temporary file 
for a NoContent URL.  But it works fine.

-Eric Bloch
bloch@incrementalimages.com