@ARCHIVAL and overfull hboxes in sig2 field

I'm wondering if anyone has had a problem with overfull hboxes with
the data in the sig2 field. I can't get latex to break that line the
way it should. Any advice on how to get it to do this?

Otherwise, as a historian doing a lot of archival work, I absolutely
love the @ARCHIVAl . . .

Here is a short tex file and a short bib file that produce the problem:

%%%%archival.tex%%%%

\documentclass{article}
\usepackage{jurabib}
\begin{document}
Footnote.\footnote{\cite{AN3}, \cite{AN4}
.}
\bibliography{dummy}
\bibliographystyle{jurabib}
\nocite{*}
\end{document}

%%%%%%dummy.bib%%%%%%%%
@ARCHIVAL { AN3,title = {title},archive = {Archives nationales,
Paris},shortarchive = {AN},subarchive = {Sous--s\'{e}rie
F\textsuperscript{10}, Agriculture},shortsubarchive =
{F\textsuperscript{10}},sig1 = {2169},sig2 = {Bl\'{e}. Statistiques,
\'{e}tudes sur le probl\`{e}me du bl\'{e}, la politique du bl\'{e}, la
d\'{e}fense et l'organisation du march\'{e} du bl\'{e}.
1934--1937},sig3 = {},archname = {}}
@ARCHIVAL { AN4,title = {title},archive = {Archives nationales,
Paris},shortarchive = {AN},subarchive = {Sous--s\'{e}rie
F\textsuperscript{12}, Commerce et industrie},shortsubarchive =
{F\textsuperscript{12}},sig1 = {9893},sig2 = {Imporateurs et
exportateurs, commissaires, courtiers, transitaires, etc., agence
g\'{e}n\'{e}rale franco--am\'{e}ricaine, 1913--1919},sig3 =
{},archname = {}}






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