1. Disable url cache in your browser. For Firefox: go to about:config and switch off 'network.http.use-cache' option.
2. Create domain with web hosting and enable php support with php-fpm module on apache.
3. add .htaccess on domain with the follow strings:
RewriteEngine On
RewriteBase /
RewriteRule ^(.*)\.php$ http://google.com [L,R=301]
4. Create some index.php on domain. E.g. with phpinfo();
5. try to open web page http://<youdomain>/index.php
Actual result - this rule doesn't work.
The problem was in fact that ProxyPassMatch directive redirects all REQUEST_URI before the .htaccess rules was used.