We're using Maven 2 to build our modules. I've created the projects in
Hudson and set a build trigger to build whenever a SNAPSHOT dependency
is built. Unfortunately, it doesn't appear to do this in a
breadth-first dependency order.

i.e.

All of our projects bar one have as a parent our company wide pom,
which defines repositories, profiles, etc.

If this project is built, it kicks of a build for the world, but lots
of them are built repeatedly.

e.g. Project Common contains our common POM.

Project Alpha depends on Project Gamma and Project Common.
Project Gamma depends on Project Common only.

If Project Common gets built, Project Alpha seems to get built next
(due to alphabetic ordering somewhere?), then Project Gamma is built,
and the Project Alpha is built again, since Project Gamma has just
been built.

When we have 20 projects, this gets a little inefficient, with certain
projects being built 3 or 4 times when they really only should be
built once.