remove invalid assert

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code/trunk@10354 a83610d8-ad2a-0410-a6ab-fc0612d85776
fix auto_sequential logic

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code/trunk@10355 a83610d8-ad2a-0410-a6ab-fc0612d85776