db: fix level-js iterators.

lib/db/level.js

@@ -105,11 +105,18 @@ function Iterator(db, options) {
   options.keyAsBuffer = false;
   this.db = db;
   this.iter = db.level.iterator(options);
+  this._end = false;
 }
 
 Iterator.prototype.next = function(callback) {
   var self = this;
   this.iter.next(function(err, key, value) {
+    // Hack for level-js: it doesn't actually
+    // end iterators -- it keeps streaming keys
+    // and values.
+    if (self._end)
+      return;
+
     if (err) {
       callback(err);
       return;
@@ -137,6 +144,7 @@ Iterator.prototype.seek = function seek(key) {
 };
 
 Iterator.prototype.end = function end(callback) {
+  this._end = true;
   this.iter.end(callback);
 };