There is a post.php in the root directory ... RewriteCond %{REQUEST_FILENAME} !-f may match as "/info" calls "/info.php"
It's possible to bypass this problem this this rewrite condition :
## BEGIN PunBB
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f [OR]
RewriteCond %{REQUEST_FILENAME} "post"
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . rewrite.php [L]
</IfModule>
# END PunBB