texlive 2020 pdflatex waits for something

[Richard J. Mathar]

I've finally managed to uninstall texlive2017 of the openSUSE 15.2 standard  distro
to move on to texlive2020:
- ran a few hundert times the zypper rm  on the texlive packages
- removed /var/lib/texmf /etc/texmf /var/cache/texmf
- edited TEXMFHOME in ~/texlive/2020/texmf-dist/web2c/texmf.cnf
   so it is the same as in ~/texlive/2020/texmf.cnf
  (apparently install-tl only changes one of the two texmf.cnf 
  but not the other...)
- removed also libtexlua52-5
- finally (that was the key point of removing the 2017-05-14 outputs of pdflatex)
  cd ~/.texlive2020 ; rm -rf *

The only problem that remains (and that was actually the trigger to 
replace texlive 2017 by texlive 2020) is that a file with a \tableofcontents,
book document and something like > 18 parts will only show the first
page of the table of contents in the .dvi or .pdf file (although the .toc
is complete with all parts). Apparently there are some optional page breaks missing
in the \tableofcontents handler. Example:

\documentclass{book}
\begin{document}
\tableofcontents
\part{kap 1 }
1
\part{kap 2 }
2
\part{kap 3 }
3
\part{kap 4 }
4
\part{kap 5 }
5
\part{kap 6 }
6
\part{kap 7 }
7
\part{kap 8 }
8
\part{kap 9 }
9
\part{kap 10 }
10
\part{kap 11 }
11
\part{kap 12 }
12
\part{kap 13 }
13
\part{kap 14 }
14
\part{kap 15 }
15
\part{kap 16 }
16
\part{kap 17 }
17
\part{kap 18 }
18
\part{kap 19 }
19
\part{kap 20 }
20
\part{kap 21 }
21
\part{kap 22 }
22
\end{document}