powerdns: fix for several slaves with same origin

the name of constructed records should be unique so use the slave
reference instead of the "origin" parameter to be sure it is unique.

Before this change, if 2 slaves have the same origin parameter
"foo.com", we have the following in zone-files.yml:

    [...]
    sa.continent.foo.com:
      - cname: cname.of.slave1.for.sa
    [...]
    sa.continent.foo.com:
      - cname: cname.of.slave2.for.sa

So only the cname for slave2 will be used.

software/powerdns/buildout.hash.cfg

@@ -34,4 +34,4 @@ md5sum = c4dc8c141d81b92d92cdb82ca67a13ee
 
 [template-zones-file]
 _update_hash_filename_ = template/zones-file.yml.jinja2
-md5sum = c820a4f53c3e7706f51a5e0be3a8cf74
+md5sum = 03037141ad1d3467ae878c9798724f70

software/powerdns/template/zones-file.yml.jinja2

@@ -48,6 +48,8 @@ domains:
 
     {%- for slave in slave_instance_list %}
 
+    {%-   set origin = slave['origin'] %}
+    {%-   set unique_slave_id = slave['slave_reference'] %}
     {#-   Set the RR to use for each region, as described in
           'slave-instance-powerdns-input-schema.json' #}
     {%-   set rr_dict = {} %}
@@ -71,8 +73,7 @@ domains:
           right RR (thanks to 'rr_dict') #}
     {%-   for placeholder, code2region in world_split.items() %}
     {%-     for code, region in code2region.items() %}
-    {%-       set origin = slave['origin'] %}
-    {{ code }}.{{ placeholder }}.{{ origin }}:
+    {{ code }}.{{ placeholder }}.{{ unique_slave_id }}:
       - cname: {{ disambiguate_domain_name(rr_dict[region], origin) }}
     {%-     endfor %}
     {%-   endfor %}
@@ -81,15 +82,16 @@ domains:
   services:
     {%- for slave in slave_instance_list %}
     {%-   set origin = slave['origin'] %}
+    {%-   set unique_slave_id = slave['slave_reference'] %}
     {{ disambiguate_domain_name(slave['record'], zone) }}:
       {#- Note: Placeholders (i.e. "country." and "continent.") are used to avoid
           possible name collisions, e.g.:
           - %cc for American Samoa is 'as'
           - %cn for Asia is also 'as' #}
-      default: ['%cc.country.{{ origin }}', '%cn.continent.{{ origin }}', '{{ disambiguate_domain_name(slave['default'], origin) }}']
+      default: ['%cc.country.{{ unique_slave_id }}', '%cn.continent.{{ unique_slave_id }}', '{{ disambiguate_domain_name(slave['default'], origin) }}']
 
       # Split China's ip addresses according to ISP
       {%- for ip_range, country_code in china %}
-      {{ ip_range }}: {{ country_code }}.country.{{ origin }}
+      {{ ip_range }}: {{ country_code }}.country.{{ unique_slave_id }}
       {%- endfor %}
     {%- endfor %}