namespace problem with RequestPathIntrospection

[submitted on behalf of Sergei Serdyuk]

RequestPathIntrospection#remove_namespace behaves incorrectly by stripping the front forward slash if controller_path != controller_name but namespace_segments is empty. Because of the lost slash #segments_for_path_and_keys would later chop of the first character of the first path segment. I added an additional check as following:

def remove_namespace(path)
  (controller_path != controller_name) && !namespace_segments.empty? ? path.sub(%r(^/#{namespace_segments.join('/')}), '') : path
end