fix($browser): prevent infinite digest if changing hash when there is no hashPrefix

The `window.location.hash' setter will strip of a single leading hash character
if it exists from the fragment  before joining the fragment value to the href
with a new hash character.

This meant that if we want the fragment to lead with a hash character, we
must do `window.location.hash = '##test'` to ensure that the first hash
character in the fragment is not lost.

The `$location.hash` setter works differently and assumes that the value
passed is the the full fragment, i.e. it does not attempt to strip off a
single leading hash character.

Previously, if you called, `$location.hash('#test')`, the leading hash was
being stripped and the resulting url fragment did not contain this hash:
`$location.hash()`, then became 'test' rather than `#test`, which led to
an infinite digest.

Closes #10423
Closes #12145

Author: petebacondarwin

src/ng/browser.js

@@ -63,7 +63,7 @@ function Browser(window, document, $log, $sniffer) {
 
   function getHash(url) {
     var index = url.indexOf('#');
-    return index === -1 ? '' : url.substr(index + 1);
+    return index === -1 ? '' : url.substr(index);
   }
 
   /**

test/ng/browserSpecs.js

@@ -57,7 +57,9 @@ function MockWindow(options) {
       return getHash(locationHref);
     },
     set hash(value) {
-      locationHref = stripHash(locationHref) + '#' + value;
+      // replace the hash with the new one (stripping off a leading hash if there is one)
+      // See hash setter spec: https://url.spec.whatwg.org/#urlutils-and-urlutilsreadonly-members
+      locationHref = stripHash(locationHref) + '#' + value.replace(/^#/,'');
     },
     replace: function(url) {
       locationHref = url;

test/ng/locationSpec.js

@@ -989,6 +989,18 @@ describe('$location', function() {
         expect($browser.url()).toBe('http://new.com/a/b#!/changed');
       });
     });
+
+
+    it('should not infinitely digest if hash is set when there is no hashPrefix', function() {
+      initService({html5Mode:false, hashPrefix:'', supportHistory:true});
+      mockUpBrowser({initialUrl:'http://new.com/a/b', baseHref:'/a/b'});
+      inject(function($rootScope, $browser, $location) {
+        $location.hash('test');
+
+        $rootScope.$digest();
+        expect($browser.url()).toBe('http://new.com/a/b##test');
+      });
+    });
   });
 
   describe('wiring in html5 mode', function() {
@@ -2507,17 +2519,11 @@ describe('$location', function() {
         win.history = {
           state: options.state || null,
           replaceState: function(state, title, url) {
-            // console.log('REPLACESTATE');
-            // console.log('CURRENT', win.location.href, win.history.state);
-            // console.log('NEW', url, state);
             win.history.state = copy(state);
             if (url) win.location.href = url;
             jqLite(win).triggerHandler('popstate');
           },
           pushState: function(state, title, url) {
-            // console.log('PUSHSTATE');
-            // console.log('CURRENT', win.location.href, win.history.state);
-            // console.log('NEW', url, state);
             win.history.state = copy(state);
             if (url) win.location.href = url;
             jqLite(win).triggerHandler('popstate');
@@ -2529,6 +2535,9 @@ describe('$location', function() {
           get href() { return parser.href; },
           set href(val) { parser.href = val; },
           get hash() { return parser.hash; },
+          // The parser correctly strips on a single preceding hash character if necessary
+          // before joining the fragment onto the href by a new hash character
+          // See hash setter spec: https://url.spec.whatwg.org/#urlutils-and-urlutilsreadonly-members
           set hash(val) { parser.hash = val; },
 
           replace: function(val) {