Eclipse ant build gives "Another singleton version selected", how can I stop that?

Question

We run org.eclipse.ant.core.antRunner to build our plugins and RCP projects. In the build logs we get a ton of messages like:

[eclipse.buildScript] Bundle org.eclipse.X:  
[eclipse.buildScript]   Another singleton version selected: org.eclipse.equinox.X_1.0.4.v20081112-1019

The reason is clear; There are two different versions of a particular bundle and it chose the latest. We cannot change the Eclipse installation to remove the older plugins, so what can be done to get rid of these messages?

Bonusquestion: What class prints out these messages? One option could be to create our own version where these messages are never shown.

Edit:
Stackoverflow suggested this question:
http://stackoverflow.com/questions/148641/customizing-antrunner-output
From there I found this page:
http://ant.apache.org/manual/listeners.html
which contains more info of ant logger and listeners.

Answer 1

Starting in Eclipse 3.5, the messages can be turned off by setting suppressResolutionErrors=true in your build configuration build.properties file. (This was actually added to speed up the unit tests.)

The messages are printed in org.eclipse.pde.internal.build.site.BuildTimeSite#getRegistry()