Also update the unencrypted size of files when creating them with emp…

…ty content

Signed-off-by: Julius Härtl <jus@bitgrid.net>

lib/private/Files/Stream/Encryption.php

@@ -528,6 +528,7 @@ protected function readCache() {
 	 */
 	protected function writeHeader() {
 		$header = $this->util->createHeader($this->newHeader, $this->encryptionModule);
+		$this->fileUpdated = true;
 		return parent::stream_write($header);
 	}