Emacs hangs when using tramp with su

[Mathias Millet]

Hi everyone,
After reinstalling my system, I found out that I couldnt have tramp working anymore, it hangs right after i enter my password.

Here is what exactly happens : I type in C-x C-f /su:root@localhost: Here emacs asks for my password, which I provide. It then hangs, showing the above string in the minibuffer, and after some time : Tramp: Waiting for prompts from remote shell

After i cancel the operation, i have :

Here is what is in the tramp/su root@localhost buffer :

Password: Password: 
su: incorrect password

Process *tramp/su root@localhost* exited abnormally with code 125

And here is what's in debug tramp/su root@localhost :
http://pastebin.com/0CKD1yM3

The last line :

 17:13:59.988240 tramp-file-name-handler (1) # Interrupt received in operation (file-exists-p /su:root@localhost:) 

seems to say that the hangs happens inside tramp-file-name-handler or file-exists-p /su:root@localhost:, but i don't really know what to do with that...

I have no idea of what might cause this, the installation is just really new (I don't remember if this worked at some point, but there was no problem at all before I reinstall).
So if anyone has an idea of what might cause this, I've been searching but couldn't find anything really usefull...

Thanks