Why is .htaccess ignoring “RewriteCond %{HTTPS} !on [NC]”?

Question

Since I declare it should only redirect if it is NOT an "https://" request, this code should not redirect from index.rd1.html to index.rd2.html if I type " https://example.com/index.rd1.html " in the url, but it does. Why?

RewriteEngine On
RewriteCond %{HTTPS} !on [NC]
RewriteCond %{REQUEST_URI} index.rd1.html [NC]
RewriteRule ^(.*)$ https://%{HTTP_HOST}/index.rd2.html [R=301,L]

Answer 1

It turns out that hostway.com (which is hosting the site) does not have the standard .htaccess rules. In order for it to detect https I had to add "ENV:" before HTTPS as done here:

RewriteCond %{ENV:HTTPS} !=on