serve-sessions.js
function newDestroy(sid, cb) {
      db.get(sid, function(err, session) {
        if (err) return cb(err);
        if (!session) return cb();
        db.set(sid + '_d', session, function(err) {
          if (err) return cb(err);
          oldDestroy.call(db, sid, cb);
        });
      });
    }
function newDestroy(sid, cb) {
      db.get(sid, function(err, session) {
        if (err) return cb(err);
        if (!session) return cb();
        db.set(sid + '_d', session, function(err) {
          if (err) return cb(err);
          oldDestroy.call(db, sid, cb);
        });
      });
    }
function newDestroy ( sid , cb ) { db . get ( sid , function ( err , session ) { if ( err ) return cb ( err ) ; if ( ! session ) return cb ( ) ; db . set ( sid + '_d' , session , function ( err ) { if ( err ) return cb ( err ) ; oldDestroy . call ( db , sid , cb ) ; } ) ; } ) ; }
rename instead of delete
rename instead of delete