display what goes wrong with the daemons at the end of the test suite

testsuite

@@ -52,6 +52,7 @@ section() {
 
 cleanup () {
     section "cleaning up"
+    tail "$d/"*.err
     /usr/sbin/nginx -c "$d/nginx.conf" -p "$d" -s stop 2> "$d/nginx-stop.err" || true
     kill %2 || true
     kill %1 || true