For me, it helped if i:
1) added file seam.properties (with empty contents) to the classpath. This activates the Seam deployer which then applies the VFSScanner (instead of the URLScanner that causes this error)
2) I also had to add file seam-deployment.properties to classpath, with contents:
org.jboss.seam.deployment.scanners=org.jboss.seam.integration.jbossas.vfs.VFSScanner
.. anyway, this issue is due to using URLScanner instead of VFSScanner (i.e. not activating seam deployer correctly)