Antoine Reilles writes:
 > > The problem is that there is no $PREFIX/bin/java installed by java,
 > > and so the program fails.
 > It should be provided by pkg_alternatives

Thank you.  This is indeed the problem.  Installing
pkgtools/pkg_alternatives solves it.

 > I don't know what happens if you do not have pkg_alternatives installed

What happens is that there is no $PREFIX/bin/java and anything that
requires that fails.

 > pkg_alternatives should be installed as soon as you install a package
 > providing an alternative, and i counted on that for apache-ant.

As far as I can see, this is not the case.  For example, installing
one of the java packages does not automatically install
pkgtools/pkg_alternatives.  Consequently, downstream packages (e.g.,
apache-ant) fail.

This suggests that pkgtools/pkg_alternatives is an absolute
prerequisite for at least some packages to work correctly.  I am not
sure what the best solution is, but it strikes me that this is an area
in need of improvement, not by addressing specific packages (like
apache-ant) but by providing a generic solution.

Cheers,
Brook