Users assigned context role via multiple components are counted multiple times

diff --git a/lib/accesslib.php b/lib/accesslib.php

index 45f07b4..5d3876e 100644

--- a/lib/accesslib.php

+++ b/lib/accesslib.php

@@ -3371,7 +3371,7 @@ function get_assignable_roles(context $context, $rolenamedisplay = ROLENAME_ALIA

     $extrafields = '';

     if ($withusercounts) {

-        $extrafields = ', (SELECT count(u.id)

+        $extrafields = ', (SELECT count(DISTINCT u.id)

                              FROM {role_assignments} cra JOIN {user} u ON cra.userid = u.id

                             WHERE cra.roleid = r.id AND cra.contextid = :conid AND u.deleted = 0

                           ) AS usercount';