Bug#984931: git-el,elpa-magit: fails to install: /usr/lib/emacsen-common/packages/install/git emacs failed at /usr/lib/emacsen-common/lib.pl line 19, <TSORT> line 7.

[David Bremner <david@tethera.net>]

Andreas Beckmann <anbe@debian.org> writes:

>   Install git for emacs
>   install/git: Handling install of emacsen flavor emacs
>   install/git: Byte-compiling for emacs
>   + emacs -batch -q -no-site-file -f batch-byte-compile git.el git-blame.el
>   /usr/lib/emacsen-common/packages/install/git: 26: emacs: not found
>   /usr/lib/emacsen-common/packages/install/git emacs failed at /usr/lib/emacsen-common/lib.pl line 19, <TSORT> line 7.
>   dpkg: error processing package elpa-magit (--configure):
>    installed elpa-magit package post-installation script subprocess returned error exit status 2
>   Setting up libm17n-0:i386 (1.8.0-2) ...
>   Setting up librsvg2-2:i386 (2.50.3+dfsg-1) ...
>   Setting up librsvg2-common:i386 (2.50.3+dfsg-1) ...
>   Setting up glib-networking:i386 (2.66.0-2) ...
>   Setting up libsoup2.4-1:i386 (2.72.0-2) ...
>   Setting up libsoup-gnome2.4-1:i386 (2.72.0-2) ...
>   Setting up librest-0.7-0:i386 (0.8.1-1.1) ...
>   Setting up libgtk-3-0:i386 (3.24.24-3) ...
>   Setting up libgtk-3-bin (3.24.24-3) ...
>   Setting up emacs-gtk (1:27.1+1-3) ...
>   update-alternatives: using /usr/bin/emacs-gtk to provide /usr/bin/emacs (emacs) in auto mode
>   update-alternatives: using /usr/bin/emacs to provide /usr/bin/editor (editor) in auto mode

As far as I can see, the problem is that the setup for elpa-magit and
git-el both call "emacs", but that does not exist until the
update-alternatives is called. So there seems to be a race condition
here where emacs-gtk (or whatever is providing /usr/bin/emacs) needs to
run its postinst before any add-on package wanting to do byte
compilation.

Somewhat to my surprise I could duplicate this failure with

         $ sudo schroot -r -c test apt install git-el elpa-magit

where test is an up to date sid chroot.