MANIFEST.MF is not used when specified in configuration for a WAR format assembly

When you try to specify a manifestFile for an assembly with war format, the manifest file specified is not used.

I have attached a zip archive which contains a maven project that reproduces the bug. The assembly generated during the package phase and named myArtifactId-1.0.0-source.war contains a manifest file, but not the one specified in the maven-assembly-plugin configuration in the pom.

I tried different versions 2.1 and 2.2-beta-2 with jar and war assembly formats, here's the behavior description:
maven-assembly 2.1 + war assembly format >>>>>>> good manifest file included
maven-assembly 2.2-beta-2 +war assembly format >>>>>>> empty manifest file
maven-assembly 2.1 + jar assembly format >>>>>>> good manifest file included
maven-assembly 2.2-beta-2 + jar assembly format >>>>>>> good manifest file included

The workaround is to use version 2.1 of the maven-assembly-plugin.