Revert "le pb de #773 est un bug de calc latex3/latex2e#58"

This reverts commit 3d68aa9.

Bon, ok, je devrais utiliser un = et pas un \setlength

issue773.tex

@@ -0,0 +1,43 @@
+\listfiles
+\documentclass[paper=a4,10pt,DIV=classic]{scrbook}
+\usepackage[latin,german]{babel} 
+\usepackage[T1]{fontenc}
+\usepackage{textcomp}
+\setlength{\overfullrule}{.45em}
+\usepackage{blindtext}
+\usepackage[series={A},noeledsec,noledgroup]{reledmac}
+\usepackage{reledpar}
+%\usepackage{calc}
+\tracingmacros2
+\tracingassigns2
+
+\begin{document}
+\chapter{Das Beispiel}
+
+\section{Einleitung}
+
+\blindtext[2]
+
+\begin{pages}
+\begin{Leftside}
+\beginnumbering
+
+\pstart[\section{Der linke Text}]
+\begin{otherlanguage}{latin}
+  \noindent\blindtext[2]
+\end{otherlanguage}
+\pend
+\endnumbering
+\end{Leftside}
+
+\begin{Rightside}
+\beginnumbering
+
+\pstart[\section{Der rechte Text}]
+\noindent\blindtext[2]
+\pend
+\endnumbering
+\end{Rightside}
+\end{pages}
+\Pages
+\end{document}