I found it strange too that line number seemed wrong. line 510 is precisely the end of the function... who knows. The version I was using was the one in SVN (569), no added hacks.

I have deactivated zip support and it is working fine without it. Maybe it would be good that someone confirms it is working ok in "zip-supported servers".

I think that the code was added for someone whose PHP did not have ZIP support. I am releasing a patch which will remove the code from functions.php to a file pclZip.php. Then functions.php will include that file if the zip_open() function is not defined. Should work, but since I don't get the error, I can't be sure.

I tried with and without zip support. I didn't get the error any more, i will try later to upload a zip in both modes.