Legacy redirects on sub-directory installs include the site slug.

[peterwilsoncc]

When enabling legacy redirects on a sub-directory install, the redirect goes to the alias domain + path.

Alias: customdomain.com
Site URL: msinstall.com/sub-site/
Redirects to: customdomain.com/sub-site/

The issue appears to come from these lines, as the site path ought to be excluded on sub-directory installs.

Mercator-Redirect/redirect.php

Lines 143 to 147 in 8f85efd

	if ( $_SERVER['HTTP_HOST'] !== $mapping->get_domain() ) {
	$domain = $mapping->get_domain();
	$path = $mapping->get_site()->path;
	redirect( $domain . $path );
	} else {

[peterwilsoncc]

Looks like it is the redirect() function instead, patch in coming.