Bug#1090910: libadwaita-1: autopkgtest fails in unshare sbuild

[Jeremy Bícha]

Source: libadwaita-1
Version: 1.6.2-1

I am using sbuild 0.87.1ubuntu3 from Ubuntu 25.04
A fairly simply config:
$chroot_mode = 'unshare';
$run_autopkgtest = 1;

And I am building with sbuild -d unstable

The build succeeds but the autopkgtest fails.

autopkgtest: test command1: LIBGL_ALWAYS_SOFTWARE=true xvfb-run -a -s
"-screen 0 1024x768x24 -noreset" -e /proc/self/fd/2
./debian/tests/python-gi-test
autopkgtest: test command1: [-----------------------
_XSERVTransmkdir: ERROR: euid != 0,directory /tmp/.X11-unix will not be created.
autopkgtest: test command1: -----------------------]
autopkgtest: test command1:  - - - - - - - - - - results - - - - - - - - - -
command1             FAIL stderr: _XSERVTransmkdir: ERROR: euid !=
0,directory /tmp/.X11-unix will not be created.
autopkgtest: test command1:  - - - - - - - - - - stderr - - - - - - - - - -
_XSERVTransmkdir: ERROR: euid != 0,directory /tmp/.X11-unix will not be created.
autopkgtest: @@@@@@@@@@@@@@@@@@@@ summary
build-test           FAIL stderr: _XSERVTransmkdir: ERROR: euid !=
0,directory /tmp/.X11-unix will not be created.
command1             FAIL stderr: _XSERVTransmkdir: ERROR: euid !=
0,directory /tmp/.X11-unix will not be created.


This failure does not happen if I remove the -e /proc/self/fd/2
additions from https://salsa.debian.org/gnome-team/libadwaita/-/commit/36fcefcf77

This is with the xorg-server 2:21.1.15-2 packages which was enough to
get Salsa CI working again for us:
https://salsa.debian.org/gnome-team/libadwaita/-/pipelines/772837/

Thank you,
Jeremy Bícha