\Hy@SaveLastskip/\Hy@RestoreLastskip suppress breakpoints

[u-fischer]

From https://tex.stackexchange.com/q/548778/2388

\Hy@SaveLastskip\Hy@RestoreLastskip as issued for example by \refstepcounter removes possible breakpoints:

\documentclass{article}

\usepackage{hyperref}  %
\textheight 3cm

\begin{document}
\begin{minipage}{5cm}
\rule{1cm}{2cm}
\end{minipage}

%\refstepcounter{section}
\makeatletter \Hy@SaveLastskip\Hy@RestoreLastskip\makeatother
\begin{minipage}{5cm}
\rule{1cm}{2cm}
\end{minipage}

\end{document}

A suggested fix is

\documentclass{article}

\usepackage{hyperref}  %
\textheight 3cm

\makeatletter
\def\Hy@SaveLastskip{%
  \let\Hy@RestoreLastskip\relax
  \ifvmode
    \ifdim\lastskip=\z@
      \ifnum\lastnodetype=11 %not sure this is needed really  %<--new
        \let\Hy@RestoreLastskip\nobreak
      \else                                           %new
        \let\Hy@RestoreLastskip\relax %new
      \fi                                                 %new
    \else
      \begingroup
        \skip@=-\lastskip
        \edef\x{%
          \endgroup
          \def\noexpand\Hy@RestoreLastskip{%
            \noexpand\ifvmode
              \noexpand\nobreak
              \vskip\the\skip@
              \vskip\the\lastskip\relax
            \noexpand\fi
          }%
        }%
      \x
    \fi
  \else
    \ifhmode
      \ifdim\lastskip=\z@
        \let\Hy@RestoreLastskip\nobreak
      \else
        \begingroup
          \skip@=-\lastskip
          \edef\x{%
            \endgroup
            \def\noexpand\Hy@RestoreLastskip{%
              \noexpand\ifhmode
                \noexpand\nobreak
                \hskip\the\skip@
                \hskip\the\lastskip\relax
              \noexpand\fi
            }%
          }%
        \x
      \fi
    \fi
  \fi
}%
\makeatother
\begin{document}
\begin{minipage}{5cm}
\rule{1cm}{2cm}
\end{minipage}

%\refstepcounter{section}
\makeatletter \Hy@SaveLastskip\Hy@RestoreLastskip\makeatother
\begin{minipage}{5cm}
\rule{1cm}{2cm}
\end{minipage}

\end{document}