[Debconf-devel] Bug#928182: debconf: readline frontend does not show options before prompting user

[Heitor Alves de Siqueira]

Hi Colin,

Thank you for taking a look at this one. It has been reported in
Launchpad as well [0].
A summary of how we can trigger this bug would be like this:

- dpkg/apt triggers a package upgrade
- some maintainer scripts are executed with the 'run-parts' tool using
the '--report' flag (e.g. the /etc/kernel/postinst.d scripts at the
end of [1])
- run-parts sets up pipes and captures stdout/stderr from debconf
- readline frontend prints prompt before run-parts can process the
options from stdout pipe

I belive we could fix this by forcing readline to always use stdout if
both stdout and stderr are pipes (since that most likely means debconf
is running under run-parts).
>From what I've tested, the attached patch works correctly for this
case. Do you think that patch would be an appropriate solution?

Thanks,
Heitor

[0] https://bugs.launchpad.net/bugs/1822270
[1] https://termbin.com/c92p
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