fix seed tool after change in cache loading (passing extent)
fix seed tool after change in cache loading (passing extent)

--HG--
branch : 0.9.1.x

mapproxy/mapproxy,geoadmin/mapproxy,olt/mapproxy,camptocamp/mapproxy,faegi/mapproxy,vrsource/mapproxy,procrastinatio/mapproxy,olt/mapproxy,vrsource/mapproxy,drnextgis/mapproxy,kaiCu/mapproxy,Anderson0026/mapproxy,mapproxy/mapproxy,kaiCu/mapproxy,geoadmin/mapproxy,camptocamp/mapproxy,drnextgis/mapproxy,procrastinatio/mapproxy,Anderson0026/mapproxy,faegi/mapproxy