add_rewrite_rule on multisite doesn’t work

Question

It seems the problem is not with add_rewrite_rule rather with the .htaccessfile for the multi site.

One of the test addresses was

http://example.com/foobar/def/whatever.php

Here’s a part of the htaccess which causes the result (Line 2)

RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]

If I comment this line out it works as expected but it may break other thing. So you have to add your own rule above the latest block:

RewriteRule ^([_0-9a-zA-Z-]+/)?foobar/(abc|def|ghi)/(.+)(/(\d.+))$ index.php?my_action=$2&my_name=$3&my_version=$5 [R=301,L]