stack/erp5: check propagation of testrunner url in the root partition

see 2a457867 (erp5: Rework testrunner's HTTP server, 2018-09-04), with
python3 the timing is not same and sometimes the parameter was not
propagated before root partitions promise were all solved, this add a
promise at the root partition to ensure the parameter is propagated

stack/erp5/buildout.hash.cfg

@@ -74,7 +74,7 @@ md5sum = 3f7b28085ceff321a3cb785db60f7c3e
 
 [template-erp5]
 filename = instance-erp5.cfg.in
-md5sum = e93128637acb4ebb04423cd1e2c0ce08
+md5sum = 4fd0cdd7d335baec896e36f6b63f4cf5
 
 [template-zeo]
 filename = instance-zeo.cfg.in

stack/erp5/instance-erp5.cfg.in

@@ -283,6 +283,7 @@ software-type = zope
 {%   set promise_software_url_section_name = 'promise-software-url' ~ partition_name -%}
 {%   set check_test_runner_url_section_name = 'check-test-runner-url' ~ partition_name -%}
 {%   set promise_test_runner_url_section_name = 'promise-test-runner-url' ~ partition_name -%}
+{%   set promise_testrunner_balancer_ready_section_name = 'promise-testrunner-balancer-ready-' ~ partition_name -%}
 {%   set zope_family = zope_parameter_dict.get('family', 'default') -%}
 {%   do zope_family_name_list.append(zope_family) %}
 {%   set backend_path = zope_parameter_dict.get('backend-path', '') % {'site-id': site_id} %}
@@ -317,6 +318,22 @@ config-activity-timeout = {{ dumps(current_zope_family_override_dict.get('activi
 {%   if test_runner_enabled -%}
 config-test-runner-apache-url-list = ${publish-early:{{ zope_family }}-test-runner-url-list}
 
+[{{ promise_testrunner_balancer_ready_section_name }}-executable]
+# promise to wait for balancer partition to have returned the parameter
+recipe = slapos.cookbook:check_parameter
+value = ${publish-early:{{ zope_family }}-test-runner-url-list}
+expected-not-value = not-ready
+path = ${directory:bin}/${:_buildout_section_name_}
+expected-value =
+
+[{{ promise_testrunner_balancer_ready_section_name }}]
+<= monitor-promise-base
+promise = check_command_execute
+name = ${:_buildout_section_name_}.py
+config-command = {{ '${' ~ promise_testrunner_balancer_ready_section_name ~ '-executable:path}' }}
+
+{% do root_common.section(promise_testrunner_balancer_ready_section_name) -%}
+
 [{{ check_test_runner_url_section_name }}]
 # Promise to wait for zope partition to receive the expected test-runner URL
 recipe = slapos.cookbook:check_parameter