Twitter Bootstrap dropdown-menu popup rendering problem

Twitter Bootstrap dropdown-menu popup renders outside window (clipped) when contained in nested pull-right and pull-left divs.

HTML

<div class="pull-left">
    <div class="pull-right">
        <div class="btn-group">                 
                <a class="btn btn-mini dropdown-toggle" data-toggle="dropdown" href="#">
                    <span>Actions</span>
                    <span class="caret"></span>
                </a>
                <ul class="dropdown-menu">
                    <li><a href="#">Item 1</a></li>
                    <li><a href="#">Item 2</a></li>
                    <li><a href="#">Item 3</a></li>
                    <li class="divider"></li>
                    <li><a href="#">Item 4</a></li>
                    <li><a href="#">Item 5</a></li>
                    
                </ul>
            </div>
    </div>
</div>

CSS

@import url('http://twitter.github.com/bootstrap/assets/css/bootstrap.css');

.container {
    margin-top: 10px;
}