In order to make a config work in different environment like Ant or Eclipse, it should be independent of any external variables. The ivysettings.xml file and property files should be sufficient to resolve any path.
Here you have set env.*
properties via Ant. You should better let Ivy do it itself with the properties
and its environment
attribute.
cf http://ant.apache.org/ivy/history/latest-milestone/settings/properties.html