maven-gae-plugin/maven-gae-plugin — pull request #32 by floatingmonkey (2012-06-05 18:06:05+00:00)
Title: enabling threadsafe in appengine-web.xml 

setting threadsafe to true is required to make it work with latest
version of GAE.

if you don't, mvn:gae will fail in 1.6.5+