create virtualenv in ./bootstrap

def bootstrap(options):
    """create virtualenv in ./bootstrap"""
    try:
        import virtualenv
    except ImportError, e:
        raise RuntimeError("virtualenv is needed for bootstrap")

    bdir = options.bootstrap_dir
    if not os.path.exists(bdir):
        os.makedirs(bdir)
    bscript = "boostrap.py"

    options.virtualenv.script_name = os.path.join(options.bootstrap_dir,
                                                  bscript)
    options.virtualenv.no_site_packages = True
    options.bootstrap.no_site_packages = True
    print options.virtualenv.script_name
    call_task('paver.virtual.bootstrap')
    sh('cd %s; %s %s' % (bdir, sys.executable, bscript))