Maven does not resolve variables within a plugin's <goal>

I have a Maven project with a Hudson profile, to be run when run under Hudson CI. The only relevant part of the Hudson profile is that the build should not fail when there are checksyle or findbugs errors. To achieve this, I've defined goal variables for both Checkstyle and Findbugs, see the attached (simplified) POM.

just run mvn:clean, and you'll get:
'${checkstyle.goal}' was specified in an execution, but not found in the plugin

(and later also for findbugs)

The variable doesn't seem to be properly resolved. What's really strange, if I do mvn effective-pom, it all looks as I'd expect it, i.e it prints out <goal>check</goal> instead of <goal>${checkstyle.goal}</goal>

This used to work perfectly under Maven 2.0.9, i.e. it would run checkstyle:check normally, but checkstyle:checkstyle under Hudson. Seems to be a regression.