X-Debbugs-Cc: michael.albinus@gmx.de

Starting with "sudo emacs -Q -f eshell", notice that the prompt looks like:

   /home/user #

Now start "emacs -Q -f eshell":

   ~ $ cd /sudo::
   /sudo:root@huginn:~ $

Notice that the prompt sigil is still "$" instead of "#". I think it 
would be better to indicate that you have a root shell by using "#" here.

Attached is a patch to do this. It adds a new function, 
'user-uid-for-file', which is aware of file name handlers. Then, Tramp 
adds the appropriate handler. Now, Eshell can use that function and we 
get the prompt sigil we expect.