Comment 0 for bug 1988145

I tried to run
http://iso.qa.ubuntu.com/qatracker/milestones/438/builds/257552/testcases/1318/results

I downloadedhttp://cdimage.ubuntu.com/ubuntu-base/focal/daily/20220829.1/focal-base-riscv64.tar.gz

mkdir base
sudo tar -C base -zxf focal-base-riscv64.tar.gz
sudo mount --bind /proc base/proc
sudo mount --bind /sys base/sys
sudo mount --bind /dev base/dev
sudo mount --bind /dev/pts base/dev/pts
sudo cp /etc/resolv.conf base/etc/
sudo chroot base

apt-get update results in:

Get:1 http://ports.ubuntu.com/ubuntu-ports focal InRelease [265 kB]
Get:2 http://ports.ubuntu.com/ubuntu-ports focal-updates InRelease [114 kB]
Err:1 http://ports.ubuntu.com/ubuntu-ports focal InRelease
  Couldn't create temporary file /tmp/apt.conf.fsIutr for passing config to apt-key
Err:2 http://ports.ubuntu.com/ubuntu-ports focal-updates InRelease
  Couldn't create temporary file /tmp/apt.conf.x7LQrB for passing config to apt-key
Get:3 http://ports.ubuntu.com/ubuntu-ports focal-backports InRelease [108 kB]
Err:3 http://ports.ubuntu.com/ubuntu-ports focal-backports InRelease
  Couldn't create temporary file /tmp/apt.conf.t2upW0 for passing config to apt-key
Get:4 http://ports.ubuntu.com/ubuntu-ports focal-security InRelease [114 kB]
Err:4 http://ports.ubuntu.com/ubuntu-ports focal-security InRelease
  Couldn't create temporary file /tmp/apt.conf.L2I28d for passing config to apt-key
Reading package lists... Done
W: GPG error: http://ports.ubuntu.com/ubuntu-ports focal InRelease: Couldn't create temporary file /tmp/apt.conf.fsIutr for passing config to apt-key
E: The repository 'http://ports.ubuntu.com/ubuntu-ports focal InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: GPG error: http://ports.ubuntu.com/ubuntu-ports focal-updates InRelease: Couldn't create temporary file /tmp/apt.conf.x7LQrB for passing config to apt-key
E: The repository 'http://ports.ubuntu.com/ubuntu-ports focal-updates InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: GPG error: http://ports.ubuntu.com/ubuntu-ports focal-backports InRelease: Couldn't create temporary file /tmp/apt.conf.t2upW0 for passing config to apt-key
E: The repository 'http://ports.ubuntu.com/ubuntu-ports focal-backports InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: GPG error: http://ports.ubuntu.com/ubuntu-ports focal-security InRelease: Couldn't create temporary file /tmp/apt.conf.L2I28d for passing config to apt-key
E: The repository 'http://ports.ubuntu.com/ubuntu-ports focal-security InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

As touch /tmp/apt.conf.fsIutr works without issues there must be a bug in how apt creates temporary files.