Allow an absolute controller path inside a module scope

Fixes #12777

1 files changed, 6 insertions, 2 deletions

diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 4bf2dc6e23..18f37dc732 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -218,8 +218,12 @@ module ActionDispatch
               controller ||= default_controller
               action     ||= default_action
 
-              unless controller.is_a?(Regexp)
-                controller = [@scope[:module], controller].compact.join("/").presence
+              if @scope[:module] && !controller.is_a?(Regexp)
+                if controller =~ %r{\A/}
+                  controller = controller[1..-1]
+                else
+                  controller = [@scope[:module], controller].compact.join("/").presence
+                end
               end
 
               if controller.is_a?(String) && controller =~ %r{\A/}