The existence of /proc/self/cgroup doesn't indicate openvz, but rather we're ensuring we still set openvz if /proc/bc/0 exists, even if ohai want's to detect this as LXC because /proc/self/cgroup exists.

It's important to be clear here, because different people add support for different virtualization systems and may not be familiar with others.

Consider wrapping these two tests in a describe block

```
# OHAI-573: Make sure we aren't misidentified as another virtualization system if /proc/self/cgroup exists"
describe "when /proc/self/cgroup exists and is populated" do
  it "sets openvz host if both /proc/bc/0 exists" do
    # blah blah
  end

  it "sets openvz guest if /proc/vz exists" do
    # blah blah
  end
end
```

You could further simplify these tests by combining with the existing tests by grouping them together

```
  shared_examples_for "openvz"
    it "should set openvz host if /proc/bc/0 exists" do
      File.should_receive(:exists?).with("/proc/bc/0").and_return(true)
      @plugin.run
      @plugin[:virtualization][:system].should == "openvz"
      @plugin[:virtualization][:role].should == "host"
    end

    it "should set openvz guest if /proc/bc/0 doesn't exist and /proc/vz exists" do
      File.should_receive(:exists?).with("/proc/bc/0").and_return(false)
      File.should_receive(:exists?).with("/proc/vz").and_return(true)
      @plugin.run
      @plugin[:virtualization][:system].should == "openvz"
      @plugin[:virtualization][:role].should == "guest"
    end

    it "should not set virtualization if openvz isn't there" do
      File.should_receive(:exists?).with("/proc/bc/0").and_return(false)
      File.should_receive(:exists?).with("/proc/vz").and_return(false)
      @plugin.run
      @plugin[:virtualization].should == {}
    end
  end

  describe "when we are checking for openvz" do
    context "/proc/self/cgroup does not exist" do
      it_behaves_like "openvz"
    end

    # OHAI-573: Make sure we aren't misidentified as another virtualization system if /proc/self/cgroup exists"
    context "/proc/self/cgroup exists" do
      before do
        # put your test code that populates /proc/self/cgroup here
      end

      it_behaves_like "openvz"
    end
  end
```

And of course, copy these tests to master and make sure they fail on master, then make sure they pass on your patched branch.