fix checking unit test

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code@10418 a83610d8-ad2a-0410-a6ab-fc0612d85776
fix test_checking

git-svn-id: svn://svn.code.sf.net/p/libtorrent/code@10419 a83610d8-ad2a-0410-a6ab-fc0612d85776