new ms site sometimes gets no roles

[RogerTheriault]

After upgrading to WPMU 2.9.2 from 2.8.6, we experienced a strange issue with NEW blogs - the blog's wp_xx_user_roles option was not adequately populated. There were no warnings, complaints, or errors at blog creation time.

Symptoms:

• the admin could not access the new blog's admin side (the exact message is "You don't have permission to view this blog. Please contact the system administrator.")
• the Add New User admin panel (for a site admin) only displays the role "Administrator" in the drop-down
• the wp_xxx_user_roles blog option contains only one "administrator" role with no capabilities (except those added by active plugins)

Looking at the install_blog function in wp-includes/wpmu-functions.php, it seems the order of function calls suddenly matters, once we changed it to the below, we were able to create new blogs with correct user roles:

        $wp_roles->_init();
        populate_roles();

The init function sets the option key for the roles but will not save anything to the db if the global $wp_user_roles already exists.

Environment:

• Have not tested against trunk
• we suspect it may not manifest itself in every installation.
• We do have plugins installed that add capabilities (eg: wp-polls) but those did not cause any issues in 2.8.6.
• we are using memcached

Steps to reproduce:

• create a new blog and administrator using the form at the bottom of the Blogs list (as a site admin)
• using the new admin's credentials, attempt to access the new blog's admin page, eg: ​http://somesite.com/newblogname/wp-admin/
• the admin is denied access and debugging indicates the user has no "read" or "edit_user" capabilities
• Note: site uber-admins can still access the new blog's admin pages

Workaround:

• copy the serialized array from the wp_xxx_user_roles option of another blog to the new blog.

[nacin]

$wp_user_roles is for static definitions of roles/capabilities. It never becomes set when the DB is used.

Possibly a plugin? Please test again on trunk and re-open if you can reproduce on occasion.