Bug#910009: exim4-config: upgrade fails when trying to execute conffile difference visualizer

[Adam D. Barratt]

Control: tags -1 + moreinfo unreproducible

On 2018-10-01 10:19, Vincent Lefevre wrote:
> Package: exim4-config
> Version: 4.91-8
> Severity: grave
> Justification: renders package unusable
[...]
> *** exim4.conf.template (Y/I/N/O/D/Z) [default=N] ? D
> dpkg (subprocess): unable to execute conffile difference visualizer
> (less -Lis): No such file or directory
> dpkg: error processing package exim4-config (--configure):
>  conffile difference visualizer subprocess returned error exit status 2

How is this possibly a bug in exim4-config? That package does not 
specify what command dpkg should use in order to page diffs.

Looking at the dpkg source code, it first checks $PAGER and if that's 
not set falls back to running the "pager" executable. That suggests one 
of two things:

- you have $PAGER set to "less -Lis" and for some reason don't have less 
available
- your /usr/bin/pager alternative points to something that's not 
installed on your system.

1) What is $PAGER set to in the environment in which you performed the 
upgrade?
2) What does /usr/bin/pager point to? (Please chase any symlinks to the 
ultmate endpoint)
3) How precisely did you invoke dpkg?

Regards,

Adam