Traceback (most recent call last):
  File "/usr/bin/pmerge", line 36, in ?
    commandline.main(subcommands)
  File "/mnt/usb/usr/lib64/python2.4/site-packages/pkgcore/util/commandline.py", line 401, in main
  File "/mnt/usb/usr/lib64/python2.4/site-packages/pkgcore/scripts/pmerge.py", line 298, in main
AttributeError: 'NoneType' object has no attribute 'all_vdbs'