NoMethodError: undefined method `configuration' for #<String inside railties?

I'm in the middle of upgrading an application to rails 2.0.2 from
1.2.5 and on startup I see this message printed out:
#<NoMethodError: undefined method `configuration' for #<String:
0x1145040>>
After some hacking I've figured out it emanates from plugin.rb in
railties (railties/lib/rails/plugin.rb) in the following block:

def evaluate_init_rb(initializer)
         if has_init_file?
           silence_warnings do
             # Allow plugins to reference the current configuration
object
             config = initializer.configuration

             eval(IO.read(init_path), binding, init_path)
           end
         end
      end

In the instances I have seen the failure occur, initializer is a
string that is the path to an init.rb file inside a plugin.

Has anyone seen this? Is it harmless? Is it because of some plugins
not doing the right thing for rails 2?

thanks