return zero as timestamp when it does not present in riak cache
return zero as timestamp when it does not present in riak cache
drnextgis/mapproxy,faegi/mapproxy,geoadmin/mapproxy,olt/mapproxy,camptocamp/mapproxy,procrastinatio/mapproxy,drnextgis/mapproxy,kaiCu/mapproxy,Anderson0026/mapproxy,olt/mapproxy,vrsource/mapproxy,kaiCu/mapproxy,mapproxy/mapproxy,faegi/mapproxy,Anderson0026/mapproxy,vrsource/mapproxy,procrastinatio/mapproxy,geoadmin/mapproxy,camptocamp/mapproxy,mapproxy/mapproxy