<br/> inside bridgehead generates invalid LaTeX #14
Description
It currently generates LaTeX that makes XeTeX crash. At least with textlive 2016.20170123-5.
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE dtbook [
<!ENTITY ndash "–">
<!ENTITY nbsp " ">
<!ENTITY test "<brl:select><brl:when-braille>braille</brl:when-braille><brl:otherwise>other</brl:otherwise></brl:select>">
]>
<?oxygen RNGSchema="http://xmlp-test/schema/dtbook-2005-3-sbs.rng" type="xml"?><dtbook xmlns:brl="http://www.daisy.org/z3986/2009/braille/" xmlns="http://www.daisy.org/z3986/2005/dtbook/" version="2005-3-sbs-full" xml:lang="de-1901">
<head>
<meta name="dc:Title" content="TESTSERVER3_1901"/>
<meta name="dc:Creator" content=""/>
<meta name="dc:Subject" content=""/>
<meta name="dc:Description" content=""/>
<meta name="dc:Publisher" content="SBS Schweizerische Bibliothek für Blinde, Seh- und Lesebehinderte"/>
<meta name="dc:Date" content="2014-01-10"/>
<meta name="dc:Type" content="Text"/>
<meta name="dc:Format" content="ANSI/NISO Z39.86-2005"/>
<meta name="dc:Identifier" content="ch-sbs-a2e12e34-cf2c-495a-b1d8-81e0e03d930a"/>
<meta name="dc:Source" content=""/>
<meta name="dc:Language" content="de-1901"/>
<meta name="dc:Rights" content=""/>
<meta name="dtb:uid" content="ch-sbs-a2e12e34-cf2c-495a-b1d8-81e0e03d930a"/>
<meta name="dtb:sourceEdition" content=""/>
<meta name="dtb:sourcePublisher" content=""/>
<meta name="dtb:sourceRights" content=""/>
<meta name="prod:series" content=""/>
<meta name="prod:seriesNumber" content=""/>
<meta name="prod:source" content=""/>
</head>
<book>
<frontmatter>
<doctitle>Diebe im Dschungel</doctitle>
<docauthor>Burkhard Wetekam</docauthor>
<level1 class="titlepage">
<level2>
<p>Rätselkrimi</p>
<p>Kurzstreckenleser</p>
<p class="sourcePublisher">Schroedel</p>
</level2>
</level1>
</frontmatter>
<bodymatter>
<level1>
<bridgehead>Bridgehead</bridgehead>
<p>Text</p>
</level1>
<level1>
<bridgehead>Bridge <br/> head</bridgehead>
<p>Text</p>
</level1>
</bodymatter>
</book>
</dtbook>