dropdown-menu button's menu renders outside browser window

Created by: inactivist

I'm relatively new to Twitter BS and encountered an odd effect with dropdown buttons. The popup menu renders outside the window/viewport, clipping the popup (and thus rendering it pretty much unusable.) The appearance is very similar to the one described in issue #3107 (closed).

JSFiddle example - screen shot:

Consider the following (admittedly unusual) floating div structure:

<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>

Patient: "Doctor, it only hurts when I laugh." Doctor: "Then don't laugh."

I'll admit that I might want to avoid the nested pull-right / pull-left structure, but... is this reasonable behavior from Bootstrap?

I'm using Bootstrap v2.0.3.