Apologies - mine seems to be a different problem - I am not using --addpkg ubuntu-desktop but I am getting a similar error message:
VMBuilder.exception.VMBuilderException: Process (['umount', '/tmp/tmpTuNycd/dev']) returned 1. stdout: , stderr: umount: /tmp/tmpTuNycd/dev: device is busy.
(In some cases useful info about processes that use
the device is found by lsof(8) or fuser(1))
Apologies - mine seems to be a different problem - I am not using --addpkg ubuntu-desktop but I am getting a similar error message:
VMBuilder. exception. VMBuilderExcept ion: Process (['umount', '/tmp/tmpTuNycd /dev']) returned 1. stdout: , stderr: umount: /tmp/tmpTuNycd/dev: device is busy.
(In some cases useful info about processes that use
the device is found by lsof(8) or fuser(1))