fix($location): strip off empty hash segments when comparing

The url is the same whether or not there is an empty `#` marker at the end.
This prevents unwanted calls to update the browser, since the browser is
automatically applying an empty hash if necessary to prevent page reloads.

Closes #9635

Author: petebacondarwin

src/ng/location.js

@@ -68,6 +68,10 @@ function stripHash(url) {
   return index == -1 ? url : url.substr(0, index);
 }
 
+function trimEmptyHash(url) {
+  return url.replace(/(#.+)|#$/, '$1');
+}
+
 
 function stripFile(url) {
   return url.substr(0, stripHash(url).lastIndexOf('/') + 1);
@@ -903,10 +907,11 @@ function $LocationProvider() {
 
     // update browser
     $rootScope.$watch(function $locationWatch() {
-      var oldUrl = $browser.url();
+      var oldUrl = trimEmptyHash($browser.url());
+      var newUrl = trimEmptyHash($location.absUrl());
       var oldState = $browser.state();
       var currentReplace = $location.$$replace;
-      var urlOrStateChanged = oldUrl !== $location.absUrl() ||
+      var urlOrStateChanged = oldUrl !== newUrl ||
         ($location.$$html5 && $sniffer.history && oldState !== $location.$$state);
 
       if (initializing || urlOrStateChanged) {

test/ng/locationSpec.js

@@ -647,6 +647,18 @@ describe('$location', function() {
     };
   }
 
+  describe('location watch', function() {
+    beforeEach(initService({supportHistory: true}));
+    beforeEach(inject(initBrowser({url:'http://new.com/a/b#'})));
+
+    it('should not update browser if only the empty hash fragment is cleared by updating the search', inject(function($rootScope, $browser, $location) {
+      $browser.url('http://new.com/a/b#');
+      var $browserUrl = spyOnlyCallsWithArgs($browser, 'url').andCallThrough();
+      $rootScope.$digest();
+      expect($browserUrl).not.toHaveBeenCalled();
+    }));
+  });
+
   describe('wiring', function() {
 
     beforeEach(initService({html5Mode:false,hashPrefix: '!',supportHistory: true}));