fix issue in clear_request_queue when we have no piece picker allocated
fix issue in clear_request_queue when we have no piece picker allocated

git-svn-id: 51f496e7cf1b55ee487494d18ee2d308bae7fe77@8099 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda

steeve/libtorrent,steeve/libtorrent,steeve/libtorrent,steeve/libtorrent,steeve/libtorrent,steeve/libtorrent