Index: wp-admin/includes/file.php
===================================================================
--- wp-admin/includes/file.php	(revision 19727)
+++ wp-admin/includes/file.php	(working copy)
@@ -323,31 +323,22 @@
 
 	$filename = wp_unique_filename( $uploads['path'], $file['name'], $unique_filename_callback );
 
-	$tmp_file = wp_tempnam($filename);
-
 	// Move the file to the uploads dir
-	if ( false === @ move_uploaded_file( $file['tmp_name'], $tmp_file ) )
+	$new_file = $uploads['path'] . "/$filename";
+	if ( false === @ move_uploaded_file( $file['tmp_name'], $new_file ) )
 		return $upload_error_handler( $file, sprintf( __('The uploaded file could not be moved to %s.' ), $uploads['path'] ) );
 
 	// If a resize was requested, perform the resize.
 	$image_resize = isset( $_POST['image_resize'] ) && 'true' == $_POST['image_resize'];
 	$do_resize = apply_filters( 'wp_upload_resize', $image_resize );
-	$size = @getimagesize( $tmp_file );
-	if ( $do_resize && $size ) {
-		$old_temp = $tmp_file;
-		$tmp_file = image_resize( $tmp_file, (int) get_option('large_size_w'), (int) get_option('large_size_h'), 0, 'resized');
-		if ( ! is_wp_error($tmp_file) ) {
-			unlink($old_temp);
-		} else {
-			$tmp_file = $old_temp;
+	if ( $do_resize ) {
+		$resized = image_resize( $new_file, (int) get_option('large_size_w'), (int) get_option('large_size_h'), false, 'resized' );
+		if ( is_wp_error( $resized ) || false === @ rename( $resized, $new_file ) ) {
+			unlink( $new_file );
+			return $upload_error_handler( $file, __( 'The resized version could not be created.' ) );
 		}
 	}
 
-	// Copy the temporary file into its destination
-	$new_file = $uploads['path'] . "/$filename";
-	copy( $tmp_file, $new_file );
-	unlink($tmp_file);
-
 	// Set correct file permissions
 	$stat = stat( dirname( $new_file ));
 	$perms = $stat['mode'] & 0000666;