4.2.8 Software installation fails

The installation of software from update sites (Help $\rangle $ Install New Software...) sometimes fails with an error saying something like:

No repository found containing: 
        osgi.bundle,org.eclipse.emf.compare,1.0.1.v200909161031
No repository found containing: 
        osgi.bundle,org.eclipse.emf.compare.diff,1.0.1.v200909161031
...

This is an eclipse/p2 bug that is referenced here.

To fix this problem: