use project_search_tabs? for user search check

app/helpers/projects_helper.rb

@@ -364,7 +364,8 @@ module ProjectsHelper
       blobs:          :download_code,
       commits:        :download_code,
       merge_requests: :read_merge_request,
-      notes:          [:read_merge_request, :download_code, :read_issue, :read_project_snippet]
+      notes:          [:read_merge_request, :download_code, :read_issue, :read_project_snippet],
+      members:        :read_project_member
     )
   end
 

app/helpers/search_helper.rb

@@ -201,4 +201,12 @@ module SearchHelper
   def limited_count(count, limit = 1000)
     count > limit ? "#{limit}+" : count
   end
+
+  def search_tabs?(tab)
+    if @project
+      project_search_tabs?(:members)
+    else
+      can?(current_user, :read_users_list)
+    end
+  end
 end

app/views/search/_category.html.haml

 - users = capture_haml do
-  - if can?(current_user, :read_users_list)
+  - if search_tabs?(:members)
     %li{ class: active_when(@scope == 'users') }
       = link_to search_filter_path(scope: 'users') do
         Users