largefiles: fix typo with s/__class/__class__/ Commit f78252429e0a (largefiles: don't create chain of __contains__ calls, 2015-03-11) introduced a typo with __class instead of __class__. Let's fix it. There are (obviously) no tests covering this code path, and I could not figure out a way to trigger it, so it remains untested. Spotted by Drew Gottlieb.