eqnarray: label on empty row discarded

[nschloe]

trafficstars

MWE:

\documentclass{article}
\begin{document}

\begin{eqnarray}\nonumber\label{coefficientgamma}
&&a\\
\end{eqnarray}

\ref{coefficientgamma}
\end{document}

LaTeX output:

LaTeXML output:

<document xmlns="http://dlmf.nist.gov/LaTeXML">
  <resource src="LaTeXML.css" type="text/css"/>
  <resource src="ltx-article.css" type="text/css"/>
  <para xml:id="p1">
    <equationgroup class="ltx_eqn_eqnarray" xml:id="S0.EGx1">
      <equation xml:id="S0.Ex1">
        <MathFork>
          <Math tex="\displaystyle a" text="a" xml:id="S0.Ex1.m2">
            <XMath>
              <XMTok font="italic" role="UNKNOWN">a</XMTok>
            </XMath>
          </Math>
          <MathBranch>
            <td align="left"><Math mode="inline" tex="\displaystyle a" text="a" xml:id="S0.Ex1.m1">
                <XMath>
                  <XMTok font="italic" role="UNKNOWN">a</XMTok>
                </XMath>
              </Math></td>
          </MathBranch>
        </MathFork>
      </equation>
    </equationgroup>
  </para>
  <para xml:id="p2">
    <p><ref labelref="LABEL:coefficientgamma"/></p>
  </para>
</document>

(Label definition missing.)