Bokeh custom ToolTips {safe} tag displays nothing

Question

When running the following Bokeh code, using the latest Bokeh and py35, the @fonts{safe} does not show up at all in the ToolTip. However when {safe} is deleted @fonts appears (not rendered of course). Does anyone know what I can do to make {safe} work? Or is there another way that I could make HTML render in ToolTips?

from bokeh.plotting import figure, output_file, show, ColumnDataSource
from bokeh.models import HoverTool

output_file("toolbar.html")

source = ColumnDataSource(
        data=dict(
            x=[1, 2, 3, 4, 5],
            y=[2, 5, 8, 2, 7],
            desc=['A', 'b', 'C', 'd', 'E'],
            imgs = [
                'http://bokeh.pydata.org/static/snake.jpg',
                'http://bokeh.pydata.org/static/snake2.png',
                'http://bokeh.pydata.org/static/snake3D.png',
                'http://bokeh.pydata.org/static/snake4_TheRevenge.png',
                'http://bokeh.pydata.org/static/snakebite.jpg'
            ],
            fonts=['<i>italics</i>',
                   '<pre>pre</pre>',
                   '<b>bold</b>',
                   '<small>small</small>',
                   '<del>del</del>'
                   ]
        )
    )

hover = HoverTool(
        tooltips="""
        <div>
            <div>
                <img
                    src="@imgs" height="42" alt="@imgs" width="42"
                    style="float: left; margin: 0px 15px 15px 0px;"
                    border="2"
                ></img>
            </div>
            <div>
                <span style="font-size: 17px; font-weight: bold;">@desc</span>
                <span style="font-size: 15px; color: #966;">[$index]</span>
            </div>
            <div>
                <span>@fonts{safe}</span>
            </div>
            <div>
                <span style="font-size: 15px;">Location</span>
                <span style="font-size: 10px; color: #696;">($x, $y)</span>
            </div>
        </div>
        """
    )

p = figure(plot_width=400, plot_height=400, tools=[hover],
           title="Mouse over the dots")

p.circle('x', 'y', size=20, source=source)

show(p)

Answer 1

It was a bug in the code. I made the changes suggested here and created this pull request. As of 1/11/2017 the fix will not be install able through pip but if you follow @bryevdv's advice you can install it through conda developer channel or build it from scratch like I did through the dev guide.