Views handlers for source and redirect are broken

Click-sorting by source URL or redirect URL is broken, because the views handlers for these fields are broken. Patch is attached -the fix is to simply use the parent query method.

The error is:

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'unknown' in 'order clause'

Query
SELECT redirect.rid AS rid, redirect.source AS redirect_source, redirect.source_options AS redirect_source_options, redirect.redirect AS redirect_redirect, redirect.redirect_options AS redirect_redirect_options, redirect.language AS redirect_language, redirect.count AS redirect_count, redirect.access AS redirect_access, users.name AS users_name, users.uid AS users_uid
FROM
{redirect} redirect
LEFT JOIN {users} users ON redirect.uid = users.uid
WHERE (( (redirect.type IN ('redirect')) ))
ORDER BY unknown ASC
LIMIT 25 OFFSET 0