Servlet mapping to "/" does not work

Using the Servlet 3.0 possibilities to add and configure servlet (ServletContainerInitializer through Spring 3.1 WebApplicationInitializer), I try to map a servlet "/", but is not working properly.
The servlet is started correctly, but the mapping does not work.
If I replace "/" by "test/*", everything work perfectly.

For information, the "/" mapping works well in a standalone tomcat 7.0.25.

I put a sample project on github that reproduce the bug : https://github.com/hikage/tomcat7-bug