`rvm gemset empty` doesn't seem to work

gistfile1.txt

~$ rvm gemset create mygems
'mygems' gemset created (/home/ben/.rvm/gems/ruby-1.9.2-p290@mygems).
~$ rvm gemset use mygems
~$ rvm gemset empty
/home/ben/.rvm/gems/ruby-1.9.2-p290@ already does not exist.
~$ rvm use 1.9.2
Using /home/ben/.rvm/gems/ruby-1.9.2-p290
~$ rvm gemset empty
/home/ben/.rvm/gems/ruby-1.9.2-p290@ already does not exist.
~$ rvm info

ruby-1.9.2-p290:

  system:
    uname:       "Linux isotope11-desktop 2.6.32-35-generic #78-Ubuntu SMP Tue Oct 11 16:11:24 UTC 2011 x86_64 GNU/Linux"
    bash:        "/bin/bash => GNU bash, version 4.1.5(1)-release (x86_64-pc-linux-gnu)"
    zsh:         " => not installed"

  rvm:
    version:      "rvm 1.9.2 by Wayne E. Seguin ([email protected]) [https://rvm.beginrescueend.com/]"

  ruby:
    interpreter:  "ruby"
    version:      "1.9.2p290"
    date:         "2011-07-09"
    platform:     "x86_64-linux"
    patchlevel:   "2011-07-09 revision 32553"
    full_version: "ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-linux]"

  homes:
    gem:          "/home/ben/.rvm/gems/ruby-1.9.2-p290"
    ruby:         "/home/ben/.rvm/rubies/ruby-1.9.2-p290"

  binaries:
    ruby:         "/home/ben/.rvm/rubies/ruby-1.9.2-p290/bin/ruby"
    irb:          "/home/ben/.rvm/rubies/ruby-1.9.2-p290/bin/irb"
    gem:          "/home/ben/.rvm/rubies/ruby-1.9.2-p290/bin/gem"
    rake:         "/home/ben/.rvm/rubies/ruby-1.9.2-p290/bin/rake"

  environment:
    PATH:         "/home/ben/.rvm/gems/ruby-1.9.2-p290/bin:/home/ben/.rvm/gems/ruby-1.9.2-p290@global/bin:/home/ben/.rvm/rubies/ruby-1.9.2-p290/bin:/home/ben/.rvm/bin:/home/ben/local/node/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:~/local/python/bin:/home/ben/local/beanstalkd/bin"
    GEM_HOME:     "/home/ben/.rvm/gems/ruby-1.9.2-p290"
    GEM_PATH:     "/home/ben/.rvm/gems/ruby-1.9.2-p290:/home/ben/.rvm/gems/ruby-1.9.2-p290@global"
    MY_RUBY_HOME: "/home/ben/.rvm/rubies/ruby-1.9.2-p290"
    IRBRC:        "/home/ben/.rvm/rubies/ruby-1.9.2-p290/.irbrc"
    RUBYOPT:      ""
    gemset:       ""


~$