Can no longer ssh in to machine as git user after upgrading to Mavericks

Double check git is a user who's allowed to ssh in to this machine.

Go to System Preferences -> Sharing and select Remote Login from the list on the left hand side of the pane.

Make sure Remote Login is turned on my checking the box next to it in the list (sounds like it is though, since you can ssh in as your own user account).

Make sure the right side of the pane either says Allow access for: All users or in the box below this option your git user appears in the list of allowed users. If it's not in the box below, press the + button to find it in a list of users registered with the system and add it to the list.

Now make sure that /Users/Shared/git is accessible to the git user.

Open Terminal and do:

cd /Users/Shared/git

Use ls -la to view the permissions on the folder:

/Users/Shared/git [ian@iansimac] [20:22]
> ls -lah
total 0
drwxr-xr-x   2 ian   wheel    68B  6 Nov 20:22 .
drwxrwxrwt  14 root  wheel   476B  6 Nov 20:22 ..

If . in the list shows the owner to be an account other than git or the permissions to be something that git can't use to access this directory you'll need to change them.

If git is the only user who should access this location, consider something like:

sudo chown -R git /Users/Shared/git
sudo chmod 755 /Users/Shared/git

If that doesn't lead to a solution, try watching your Console while attempting to ssh in to the machine as the git user to see what it says. You can filter console messages for sshd to see just ssh-related messages:

11/6/2013 8:25:54.006 PM sshd: ian [priv][53178]: USER_PROCESS: 53189 ttys001
11/6/2013 8:26:37.217 PM sshd: ian [priv][53178]: DEAD_PROCESS: 53189 ttys001
11/6/2013 8:26:41.164 PM sshd: unknown [pam][53214]: in od_record_create(): failed: 13
11/6/2013 8:26:41.164 PM sshd: unknown [pam][53214]: in od_record_create_cstring(): failed: 13
11/6/2013 8:26:42.538 PM sshd: unknown [pam][53214]: in od_record_create(): failed: 13
11/6/2013 8:26:42.538 PM sshd: unknown [pam][53214]: in od_record_create_cstring(): failed: 13
11/6/2013 8:26:42.538 PM sshd: unknown [pam][53214]: in pam_sm_authenticate(): OpenDirectory - Unable to get user record.
v11/6/2013 8:26:42.540 PM sshd[53212]: error: PAM: unknown user for illegal user foo from localhost via ::1

And failed login attempts look like the last line in the output above.