Changed if statement to elseif statement.

drupal-settings.php

@@ -79,7 +79,7 @@ $conf['cas_domain'] = 'uwaterloo.ca';
 if (is_file('/etc/pki/tls/certs/ca-bundle.crt')) {
   $conf['cas_cert'] = '/etc/pki/tls/certs/ca-bundle.crt';
 }
-if (is_file('/etc/ssl/certs/ca-certificates.crt')){
+elseif (is_file('/etc/ssl/certs/ca-certificates.crt')) {
   $conf['cas_cert'] = '/etc/ssl/certs/ca-certificates.crt';
 }
 $conf['site_403'] = 'customerror/403';