Description:
------------
On Windows, when the destination file in copy() is flocked, the destination ends up as an empty file.

On linux, the example code works as expected.

Reproduce code:
---------------
// echo foo > foo.txt
// echo bar > bar.txt
$fp = fopen('foo.txt', 'r');
@flock($fp, LOCK_EX);
copy('bar.txt', 'foo.txt');
fclose($fp);

Expected result:
----------------
c:\cat foo.txt bar.txt
foo
bar

Actual result:
--------------
c:\cat foo.txt bar.txt
bar

(File foo.txt is empty.)