Don't show fork button if user can't fork the project.

app/views/projects/forks/index.html.haml

@@ -29,14 +29,15 @@
           = link_to page_filter_path(sort: sort_value_oldest_updated, without: excluded_filters) do
             = sort_title_oldest_updated
-    - if current_user.already_forked?(@project) && current_user.manageable_namespaces.size < 2
-      = link_to namespace_project_path(current_user, current_user.fork_of(@project)), title: 'Go to your fork', class: 'btn btn-new' do
-        = icon('code-fork fw')
-        Fork
-    - else
-      = link_to new_namespace_project_fork_path(@project.namespace, @project), title: "Fork project", class: 'btn btn-new' do
-        = icon('code-fork fw')
-        Fork
+    - if current_user && can?(current_user, :fork_project, @project)
+      - if current_user.already_forked?(@project) && current_user.manageable_namespaces.size < 2
+        = link_to namespace_project_path(current_user, current_user.fork_of(@project)), title: 'Go to your fork', class: 'btn btn-new' do
+          = icon('code-fork fw')
+          Fork
+      - else
+        = link_to new_namespace_project_fork_path(@project.namespace, @project), title: "Fork project", class: 'btn btn-new' do
+          = icon('code-fork fw')
+          Fork
 .projects-list-holder