we have an issue using excluded_uri_prefixes and naming a content within our siteaccess the same prefix as item in excluded_uri_prefixes.

This is the Yaml Configuration : 

ezpublish: 
    system: 
        my_siteaccess: 
            content: 
                tree_root: 
                    excluded_uri_prefixes: [ "/Ressources/", "/Media/" ] 

Our siteaccess is level 2 below rootLocation /home and /Ressources is at the same level as our siteaccess.rootLocation /My_Siteaccess

Home
    Ressources
    My_Siteaccess
        Ressources-Educatives

On frontoffice, links are good in our menu (/My_Siteaccess/Ressources-Educatives) but when clicking on it, urlAliasGenerator recognise prefixes /Ressources and redirect on it, even if we add a slash at the end of /Ressources/.

Recognition is done in UrlAliasGenerator.isUriPrefixExcluded function.
cf. https://github.com/ezsystems/ezpublish-kernel/blob/master/eZ/Publish/Core/MVC/Symfony/Routing/Generator/UrlAliasGenerator.php#L149

As you trim all slashes from item in excluded_uri_prefixes, the ending slash is not taken in account and all ressources starting with /Ressources would be redirected to /Ressources. 
I solve the issue by changing : 

$excludedPrefix = '/' . trim($excludedPrefix, '/');

to `ltrim`

$excludedPrefix = '/' . ltrim($excludedPrefix, '/');

and it works fine, i'm not redirected anymore on /Ressources when accessing /Ressources-Educatives

Another workaround should be :

public function isUriPrefixExcluded($uri) 
{ 
    $uri = preg_match('/\/$/', $uri) ? $uri : $uri . '/'; 
    foreach ($this->excludedUriPrefixes as $excludedPrefix) 
    { 
        $excludedPrefix = '/' . trim($excludedPrefix, '/') . '/'; 
        if (mb_stripos($uri, $excludedPrefix) === 0) 
        { 
             return true; 
        } 
    } 

    return false; 
}

Hope it helps.

ps: i open a support.ez.no issue asap.