500 Internal Server Error with non-existent files multisite

Hi,

I’ve noticed that I’ve a lot of “Internal Server Error” in my multisite instalation. Looking at the logs these errors happens when somebody try to access to a non existent file inside wp-content, wp-admin, or so.

I’ve found this old thread from the old WP mu forum: http://mu.wordpress.org/forums/topic/12676

And the last trick works for me:

I change this block:
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule . - [L]

to:
RewriteCond %{ENV:REDIRECT_STATUS} !^$ [OR]
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule . - [L]

But I don’t know why this is not fixed yet in the .htaccess directives when I activate multisite or if is a smart fix.

Can anyone help with this issue?