If we unbox, and TeX decides to break at an existing hyphen, then the
ligature machinery misfires and we get an en-dash at the break.
%<+strayman> [2020/09/07 1.11 Straylight document class]
% \end{meta-comment}
%
-% \CheckSum{3173}
+% \CheckSum{3172}
%% \CharacterTable
%% {Upper-case \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
%% Lower-case \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
\vskip\abovecaptionskip%
\sbox\@tempboxa{\captionstyle{#1}{#2}}%
\ifdim\wd\@tempboxa>\hsize%
- \unhbox\@tempboxa\par%
+ \captionstyle{#1}{#2}\par%
\else%
\hb@xt@\hsize{\hfil\unhbox\@tempboxa\hfil}%
\fi%