Fix login-if-?next behavior

* for more context, see https://basecamp.com/1892446/projects/631155-devops/messages/4719963-strange-caching

common/djangoapps/student/views.py

@@ -52,6 +52,10 @@ def csrf_token(context):
             ' name="csrfmiddlewaretoken" value="%s" /></div>' % (csrf_token))
 
 
+# NOTE: This view is not linked to directly--it is called from
+# branding/views.py:index(), which is cached for anonymous users.
+# This means that it should always return the same thing for anon
+# users. (in particular, no switching based on query params allowed)
 def index(request, extra_context={}, user=None):
     '''
     Render the edX main page.
@@ -82,8 +86,6 @@ def index(request, extra_context={}, user=None):
                                              domain=domain)
     context = {'universities': universities, 'entries': entries}
     context.update(extra_context)
-    if request.REQUEST.get('next', False):
-        context['show_login_immediately'] = True
     return render_to_response('index.html', context)
 
 def course_from_id(course_id):

lms/static/js/query-params.js

+// http://james.padolsey.com/javascript/bujs-1-getparameterbyname/
+function getParameterByName(name) {
+    var match = RegExp('[?&]' + name + '=([^&]*)')
+                    .exec(window.location.search);
+
+    return match ?
+        decodeURIComponent(match[1].replace(/\+/g, ' '))
+        : null;
+}

lms/templates/index.html

@@ -145,12 +145,22 @@
   </div>
 </section>
 
+
+<%block name="js_extra">
+ <script type="text/javascript" src="${static.url('js/query-params.js')}"></script>
+   <script type="text/javascript"">
+      $(window).load(function() {
+         if(getParameterByName('next')) {
+              $('#login').trigger("click");
+         }
+      })
+   </script>
+</%block>
+
 % if show_signup_immediately is not UNDEFINED:
+  ## NOTE: This won't work in production, because anonymous views are cached, so it will
+  ## show either with or without this extra js for 3 minutes at a time.
 <script type="text/javascript">
-$(window).load(function() {$('#signup_action').trigger("click");});
-</script>
-% elif show_login_immediately is not UNDEFINED:
-<script type="text/javascript">
-  $(window).load(function() {$('#login').trigger("click");});
+  $(window).load(function() {$('#signup_action').trigger("click");});
 </script>
-% endif
+% endif
\ No newline at end of file

lms/templates/university_profile/base.html

@@ -14,4 +14,17 @@
       <%block name="university_description" />
     </section>
   </section>
+
+<%block name="js_extra">
+   <script type="text/javascript" src="${static.url('js/query-params.js')}"></script>
+   <script type="text/javascript"">
+      $(window).load(function() {
+         if(getParameterByName('next')) {
+              $('#login').trigger("click");
+         }
+      })
+   </script>
+</%block>
+
+
 </section>