404 for "newbloguser" url in Welcome email

Hello,

I have a brandnew, completely clean installation of WP 3.5.1 on Ubuntu 13.04. I set it up for multisite according to the documentation and created 2 sites. I then created 2 users, and tried to add them to one of the sites. When the user received an email it contained a link that looks like this

https://beta.wp-custom.local/newbloguser/a87ff/

Clicking on that link results in a 404 error.

From doing a little digging it appears this link is generated by the file user-new.php on line 88 however I cannot see anywhere that there is a mapping for “newbloguser” to a specific PHP page/resource. Amy I missing something?

Note: I saw two other posts about this and both were closed without answers.