Dependency-filename appended as subdirectory of outputDirectory of dependencySet when unpackOptions/filtered = true

I have attached a minimal project demonstrating the different behavior of unpacking a dependencySet when unpackOptions/filtered is set to either true or false. With value of false, the contents of the dependency is correctly unpacked to the declared outputDirectory, but with filtered=true the contents is unpacked to a subdirectory of outputDirectory with the same name as the dependency's filename.

In the attached project I have declared a dependency to maven-default-skin (randomly choosed artifact). In my assembly descriptor (src/main/assembly/unpack-deps.xml) I have declared the dependency to be unpacked to deps, but the contents of maven-default-skin ends up in the folder 'deps/maven-default-skin-1.0-SNAPSHOT.jar/' in my resulting zip assembly. Changing filtered to false correctly unpacks to the 'deps/' folder.