diff -r 000000000000 -r 6474c204b198 toolkit/components/autocomplete/tests/unit/test_660156.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/components/autocomplete/tests/unit/test_660156.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,99 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Search object that returns results at different times.
+ * First, the search that returns results asynchronously.
+ */
+function AutoCompleteAsyncSearch(aName, aResult) {
+  this.name = aName;
+  this._result = aResult;
+}
+AutoCompleteAsyncSearch.prototype = Object.create(AutoCompleteSearchBase.prototype);
+AutoCompleteAsyncSearch.prototype.startSearch = function(aSearchString, 
+                                                         aSearchParam, 
+                                                         aPreviousResult, 
+                                                         aListener) {
+  setTimeout(this._returnResults.bind(this), 500, aListener);
+};
+
+AutoCompleteAsyncSearch.prototype._returnResults = function(aListener) {
+  var result = this._result;
+
+  result.searchResult = Ci.nsIAutoCompleteResult.RESULT_SUCCESS;
+  aListener.onSearchResult(this, result);
+};
+
+/**
+ * The synchronous version
+ */
+function AutoCompleteSyncSearch(aName, aResult) {
+  this.name = aName;
+  this._result = aResult;
+}
+AutoCompleteSyncSearch.prototype = Object.create(AutoCompleteAsyncSearch.prototype);
+AutoCompleteSyncSearch.prototype.startSearch = function(aSearchString, 
+                                                        aSearchParam, 
+                                                        aPreviousResult, 
+                                                        aListener) {
+  this._returnResults(aListener);
+};
+
+/**
+ * Results object
+ */
+function AutoCompleteResult(aValues, aDefaultIndex) {
+  this._values = aValues;
+  this.defaultIndex = aDefaultIndex;
+}
+AutoCompleteResult.prototype = Object.create(AutoCompleteResultBase.prototype);
+
+
+/** 
+ * Test AutoComplete with multiple AutoCompleteSearch sources, with one of them
+ * (index != 0) returning before the rest.
+ */
+function run_test() {
+  do_test_pending();
+
+  var results = ["mozillaTest"];
+  var inputStr = "moz";
+
+  // Async search
+  var asyncSearch = new AutoCompleteAsyncSearch("Async", 
+                                                new AutoCompleteResult(results, -1));
+  // Sync search
+  var syncSearch = new AutoCompleteSyncSearch("Sync",
+                                              new AutoCompleteResult(results, 0));
+  
+  // Register searches so AutoCompleteController can find them
+  registerAutoCompleteSearch(asyncSearch);
+  registerAutoCompleteSearch(syncSearch);
+    
+  var controller = Cc["@mozilla.org/autocomplete/controller;1"].
+                   getService(Ci.nsIAutoCompleteController);  
+  
+  // Make an AutoCompleteInput that uses our searches
+  // and confirms results on search complete.
+  // Async search MUST be FIRST to trigger the bug this tests.
+  var input = new AutoCompleteInputBase([asyncSearch.name, syncSearch.name]);
+  input.completeDefaultIndex = true;
+  input.textValue = inputStr;
+
+  // Caret must be at the end. Autofill doesn't happen unless you're typing
+  // characters at the end.
+  var strLen = inputStr.length;
+  input.selectTextRange(strLen, strLen);
+
+  controller.input = input;
+  controller.startSearch(inputStr);
+
+  input.onSearchComplete = function() {
+    do_check_eq(input.textValue, results[0]);
+
+    // Unregister searches
+    unregisterAutoCompleteSearch(asyncSearch);
+    unregisterAutoCompleteSearch(syncSearch);
+    do_test_finished();
+  };
+}