The var task seems not to work correctly using ant
1.6.1. The "object rape" method of stealing
the "properties" field from the Project class is no longer
valid since this had moved to a PropertyHelper class.
This breaks its functionality. A.o. the example in the
documentation that does <var name="x" value=""/> no
longer works; the <format/> task later on cannot use
the value anymore.
And: the documentation of the task speaks of a
(handy) "unset" attribute of the task, but this is not