Google App Engine and Grails 1.2-M2

When I was trying to create my first Google Wave robot using Grails, I noticed that Grails 1.2-M2 is not compatible with the Google App Engine. Reverting to Grails 1.1.1 made the example in http://www.grails.org/plugin/app-engine work.

Note: In the site, appcfg.sh's permissions must be changed to be able to use $APPENGINE_HOME/bin/appcfg.sh update ./target/war