slaprunner: correctly list custom-frontend-url-ready-promise in parts

fixup of 6fbc6e15

software/slaprunner/buildout.hash.cfg

@@ -18,7 +18,7 @@ md5sum = 8d6878ff1d2e75010c50a1a2b0c13b24
 
 [template-runner]
 filename = instance-runner.cfg
-md5sum = b03f39d483cb7f3554fb40092b5b89fa
+md5sum = 376ae851bb13bd88b02ecd72249a64bd
 
 [template-runner-import-script]
 filename = template/runner-import.sh.jinja2

software/slaprunner/instance-runner.cfg

@@ -37,9 +37,12 @@ common-runner-parts =
   slaprunner-frontend-promise
   httpd-frontend-promise
 {% endif %}
-{% if slapparameter_dict.get('custom-frontend-backend-url') and slapparameter_dict.get('check-custom-frontend-promise', 'false') == 'true' %}
+{% if slapparameter_dict.get('custom-frontend-backend-url') %}
+  custom-frontend-url-ready-promise
+{% if slapparameter_dict.get('check-custom-frontend-promise', 'false') == 'true' %}
   custom-frontend-promise
 {% endif %}
+{% endif %}
 ## Monitoring part
   monitor-base
   monitor-check-webrunner-internal-instance