Rewrite rules cause some URLs to fail

[wpmuguru]

From MU Trac, Ticket #215 ​http://trac.mu.wordpress.org/ticket/215

The following lines are not necessary with a vhost install and $base = '/' :

RewriteRule ^{([_0-9a-zA-Z-]+/)?(wp-.*) $2 [L]
RewriteRule} ([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]

They could conduct to an infinite rewrite loop and lead the web server to a 500 error.