The latest AS trunk build is generating the JBOSS_HOME/client/jbossall-client.jar MANIFEST.MF with unsubstituted property values:

...
Specification-Title: ${specification.title}
Specification-Version: ${specification.version}
Specification-Vendor: ${specification.vendor}
Implementation-Title: ${implementation.title}
Implementation-Version: ${implementation.version}
Implementation-Vendor: ${implementation.vendor}
Implementation-Vendor-Id: ${implementation.vendor.id}
...//rest of it

The property values don't seem to be set in the build process. Please refer to the referenced forum thread for the details.