Fix failure to request data from peers if it goes missing after being downloaded during the same session

The chunks remained marked dirty, even after the piece was marked complete. So when the piece was not complete, there was nothing to do.

client.go

@@ -2435,6 +2435,7 @@ func (me *Client) pieceHashed(t *torrent, piece int, correct bool) {
 
 func (me *Client) onCompletedPiece(t *torrent, piece int) {
 	t.pendingPieces.Remove(piece)
+	t.pendAllChunkSpecs(piece)
 	for _, conn := range t.Conns {
 		conn.Have(piece)
 		for r := range conn.Requests {