Ensure ActionView::PathSet::Path is not initialized with a precompiled path

actionmailer/lib/action_mailer/base.rb

@@ -426,7 +426,8 @@ module ActionMailer #:nodoc:
       end
 
       def template_root=(root)
-        write_inheritable_attribute(:template_root, ActionView::PathSet::Path.new(root))
+        root = ActionView::PathSet::Path.new(root) if root.is_a?(String)
+        write_inheritable_attribute(:template_root, root)
       end
     end
 

actionpack/lib/action_view/paths.rb

@@ -28,6 +28,8 @@ module ActionView #:nodoc:
       delegate :to_s, :to_str, :inspect, :to => :path
 
       def initialize(path)
+        raise ArgumentError, "path already is a Path class" if path.is_a?(Path)
+
         @path = path.freeze
         reload!
       end