Mnet - link to mnet_email.php shows when it shouldn't

when Mnet is enabled, if a user gets their password wrong on the login screen a link to Mnet_email is always shown even when SSO to Moodle isn't configured - if a site is only configured to allow their users to SSO to other sites - not the other way round, Moodle shouldn't show the link as it's useless - here's a patch that fixes it:

— a/login/index.php
+++ b/login/index.php
@@ -238,7 +238,8 @@ httpsrequired();
// TODO: if the user failed to authenticate, check if the username
if ( !empty($CFG->mnet_dispatcher_mode)
&& $CFG->mnet_dispatcher_mode === 'strict'

• && is_enabled_auth('mnet'))
  Unknown macro: {+ && is_enabled_auth('mnet') &&+ record_exists('mnet_host2service', 'publish', '1', 'serviceid', get_field('mnet_service', 'id', 'name', 'sso_sp')) ) { $errormsg .= get_string('loginlinkmnetuser', 'mnet', "mnet_email.php?u=$frm->username"); } }