bug#40577: Auctex can't open anymore documentation

[Tobias Bora]

Hello,

I don't know why, but I updated recently my .emacs file (which may downloaded a recent version of auctex), and since then I can't open documentation anymore. Indeed, if I do `C-c ? tikz <RET>` then okular starts, but is killed before opening the document. I tried with an empty configuration (emacs -Q) in a new home, and I even tried it on a completely empty (and new) user.

Here is how you can reproduce the bug:

1) On debian unstable (KDE), install emacs 1:26.3+1-1
2) create an empty folder to become the new home: mkdir /tmp/testemacs
3) start emacs: env HOME=/tmp/testemacs emacs -Q
4) install auctex: M-x package-list-packages, select auctex, and click "Install" (it should give you the version 12.2.0)
5) open a new .tex file: C-x f a.tex
6) try to open some documentation C-c ? tikz <RET>

You should then see okular starting in the trail bar, and being killed before opening. I tried to monitor what was happening with something like `while true; do ps aux | grep okular | grep -v "grep okular"; done`, and indeed, okular is started:

me        22670  0.0  0.1  88344 11696 ?        R    18:07   0:00 /usr/bin/okular /usr/share/texlive/texmf-dist/doc/generic/pgf/pgfmanual.pdf
[...]
me        22670  104  2.4 784268 195144 ?       Rl   18:07   0:02 /usr/bin/okular /usr/share/texlive/texmf-dist/doc/generic/pgf/pgfmanual.pdf
me        22670  105  0.0      0     0 ?        Zl   18:07   0:02 [okular] <defunct>

If I manually type this command "/usr/bin/okular /usr/share/texlive/texmf-dist/doc/generic/pgf/pgfmanual.pdf" is does open the requested PDF.

Any idea what's going wrong? The only idea I have is that maybe emacs kills for some reason the okular process, but no idea why...

Thanks,

Tobias Bora