Git authentication - pull as a new user

The following set of commands worked correctly

$ mkdir carboncake
$ cd carboncake
$ git init
$ git remote add origin gitosis@myserver.net:repositories/carboncake.git 
$ git pull

But when i tried pull as a different user,

$ mkdir carboncake
$ cd carboncake
$ git init
$ git remote add origin mithun@myserver.net:repositories/carboncake.git 
$ git pull

I got the following error

fatal: 'repositories/carboncake.git' does not appear to be a git repository
fatal: The remote end hung up unexpectedly

my gitosis.conf contains

[gitosis]

[group team]
writable = sweepshots
members = git_id_rsa

[group gitosis-admin]
writable = gitosis-admin
members = git_id_rsa


[repo carboncake]
description = A brand new app by Mithun.
owner = Mithun P

[group carboncake]
writable = carboncake
members = mithun @core

and the keydir contains git_id_rsa.pub KEY-----.pub mithun.pub mithun-rsa-key-20110427.pub

and the user's .ssh dir contains

mithu开发者_运维技巧n@testserver:~$ ls .ssh/
id_rsa  id_rsa.pub  mithun_rsa  mithun_rsa.pub

-- UPDATE

I tried $ git remote add origin mithun@myserver.net:carboncake.git too, but the same error.

Actually carboncake.git is located at /srv/gitosis/repositories/carboncake.git

---

To add a little plain-english clarity to @VonC's (entirely correct) answer...

gitosis (which is no longer in active development and you should be using gitolite, but this answer applies to both of them) stores each user's public keys in (in your case) ~gitosis/.ssh/authorized_keys. When a user ssh'es to the account gitosis, ssh does a cryptographic handshake, finds a line in that authorized_keys file that matches the provided key, and does whatever that line says to do. If you look at that authorized_keys file, each line supplies a command to call when that user logs in, which is a call to the gitosis process, carrying the name of the user in question.

So each user is REALLY ssh'ing to the SAME gitosis "machine" account, but the key they SSH there with fires up gitosis AS the user they are. That's how gitosis knows which user it's talking to even though they've logged into the same "machine" account named gitosis.

So every local repo you want to track to gitosis needs to be given a remote of the format gitosis@your.server:<reponame>.git.

---

mithun@myserver.net ?

By using mithun@myserver.net, you are bypassing gitosis completely, since the correct url would involve the 'git' user under which gitolite has been installed.
Every gitosis commands would involve the same 'git' user: gitosis@myserver.net (assuming a 'gitosis' account here).

Plus, you shouldn't have to specify the full path of the repo:

 git remote add origin gitosis@myserver.net:carboncake.git