skip impossible test-scenario

tests/src/Model/Storage/FilesystemStorageTest.php

@@ -78,6 +78,8 @@ class FilesystemStorageTest extends StorageTest
 	 */
 	public function testMissingFilePermissions()
 	{
+		$this->markTestIncomplete("Cannot catch file_put_content() error due vfsStream failure");
+
 		vfsStream::create(['storage' => ['f0' => ['c0' => ['k0i0' => '']]]], $this->root);
 
 		$this->root->getChild('storage/f0/c0/k0i0')->chmod(000);