FIX: Only group admins can see group edit page.

app/assets/javascripts/discourse/controllers/group.js.es6

@@ -1,4 +1,5 @@
 import { default as computed, observes } from 'ember-addons/ember-computed-decorators';
+import Group from 'discourse/models/group';
 
 var Tab = Em.Object.extend({
   @computed('name')
@@ -53,18 +54,18 @@ export default Ember.Controller.extend({
     this.get('tabs')[0].set('count', this.get('model.user_count'));
   },
 
-  @computed('model.is_group_user', 'model.is_group_owner', 'model.automatic')
-  getTabs(isGroupUser, isGroupOwner, automatic) {
+  @computed('model.is_group_owner', 'model.automatic')
+  getTabs(isGroupOwner, automatic) {
     return this.get('tabs').filter(t => {
-      let display = true;
+      let canSee = true;
 
-      if (this.currentUser && t.get('requiresGroupAdmin')) {
-        display = automatic ? false : (this.currentUser.admin || isGroupOwner);
-      } else if (t.get('requiresGroupAdmin')) {
-        display = false;
+      if (this.currentUser && t.requiresGroupAdmin) {
+        canSee = this.currentUser.canManageGroup(this.get('model'));
+      } else if (t.requiresGroupAdmin) {
+        canSee = false;
       }
 
-      return display;
+      return canSee;
     });
   }
 });

app/assets/javascripts/discourse/models/group.js.es6

@@ -17,9 +17,10 @@ const Group = RestModel.extend({
     return Em.isEmpty(value) ? "" : value;
   },
 
-  type: function() {
-    return this.get("automatic") ? "automatic" : "custom";
-  }.property("automatic"),
+  @computed('automatic')
+  type(automatic) {
+    return automatic ? "automatic" : "custom";
+  },
 
   @computed('user_count')
   userCountDisplay(userCount) {
@@ -93,6 +94,7 @@ const Group = RestModel.extend({
     });
   },
 
+
   @computed('flair_bg_color')
   flairBackgroundHexColor() {
     return this.get('flair_bg_color') ? this.get('flair_bg_color').replace(new RegExp("[^0-9a-fA-F]", "g"), "") : null;
@@ -224,7 +226,7 @@ Group.reopenClass({
 
   mentionable(name) {
     return ajax(`/groups/${name}/mentionable`, { data: { name } });
-  },
+  }
 });
 
 export default Group;

app/assets/javascripts/discourse/models/user.js.es6

@@ -500,8 +500,11 @@ const User = RestModel.extend({
 
               return summary;
            });
-  }
+  },
 
+  canManageGroup(group) {
+    return group.get('automatic') ? false : (this.get('admin') || group.get('is_group_owner'));
+  }
 });
 
 User.reopenClass(Singleton, {

app/assets/javascripts/discourse/routes/group-edit.js.es6

@@ -1,3 +1,5 @@
+import Group from 'discourse/models/group';
+
 export default Ember.Route.extend({
   titleToken() {
     return I18n.t('groups.edit.title');
@@ -7,6 +9,12 @@ export default Ember.Route.extend({
     return this.modelFor('group');
   },
 
+  afterModel(group) {
+    if (!this.currentUser || !this.currentUser.canManageGroup(group)) {
+      this.transitionTo("group.members", group);
+    }
+  },
+
   setupController(controller, model) {
     this.controllerFor('group-edit').setProperties({ model });
     this.controllerFor("group").set("showing", 'edit');