FS-11508: [mod_sofia] Make max-registrations-per-extension use extension instead of username

src/mod/endpoints/mod_sofia/sofia_reg.c

@@ -3075,7 +3075,7 @@ auth_res_t sofia_reg_parse_auth(sofia_profile_t *profile,
 		switch_assert(call_id);
 
 		sql = switch_mprintf("select count(sip_user) from sip_registrations where sip_user='%q' AND call_id <> '%q' AND sip_host='%q'",
-							 username, call_id, domain_name);
+							 sip->sip_to->a_url->url_user, call_id, domain_name);
 		switch_assert(sql != NULL);
 		sofia_glue_execute_sql_callback(profile, NULL, sql, sofia_reg_regcount_callback, &count);
 		free(sql);