• Bail out if we can't claim a chroot directory in the client (e.g. if

ssh times out)

• Support new portbuild.conf settings:
  
  client_user = user to connect to on the client (not necessarily root)
  
  sudo_cmd = If ssh'ing to a non-root user, run this command to gain root privs (set to empty string for client_user=root, or sudo for !root). Cannot require interactivity, of course.

Approved by: portmgr (self)