Comment 21 for bug 1849785

Build issue is reproducible on arm64 LP infrastructure builds.

I spawned a canonistack arm64 system to check if it is reproducible there as well for some debugging how we could fix it.

Interestingly, it does NOT FAIL on focal as-is when building on aarch64.

But as LP builds are against -proposed I Then switched to focal-proposed which upgraded this list of things:
apport/focal-proposed 2.20.11-0ubuntu11 all [upgradable from: 2.20.11-0ubuntu9]
fwupd-signed/focal-proposed 1.12+1.3.3-2 arm64 [upgradable from: 1.10+1.2.10-1ubuntu2]
fwupd/focal-proposed 1.3.3-2 arm64 [upgradable from: 1.2.10-1ubuntu2]
gawk/focal-proposed 1:5.0.1+dfsg-1 arm64 [upgradable from: 1:4.2.1+dfsg-1.1build1]
libcap2-bin/focal-proposed 1:2.27-1 arm64 [upgradable from: 1:2.25-2]
libcap2/focal-proposed 1:2.27-1 arm64 [upgradable from: 1:2.25-2]
libdebconfclient0/focal-proposed 0.250ubuntu1 arm64 [upgradable from: 0.249ubuntu1]
libfwupd2/focal-proposed 1.3.3-2 arm64 [upgradable from: 1.2.10-1ubuntu2]
libglib2.0-0/focal-proposed 2.63.1-1 arm64 [upgradable from: 2.62.1-1]
libglib2.0-bin/focal-proposed 2.63.1-1 arm64 [upgradable from: 2.62.1-1]
libglib2.0-data/focal-proposed 2.63.1-1 all [upgradable from: 2.62.1-1]
liblz4-1/focal-proposed 1.9.2-1 arm64 [upgradable from: 1.9.1-2]
libpam-cap/focal-proposed 1:2.27-1 arm64 [upgradable from: 1:2.25-2]
libpython3-all-dev/focal-proposed 3.7.5-1ubuntu1 arm64 [upgradable from: 3.7.5-1]
libpython3-dev/focal-proposed 3.7.5-1ubuntu1 arm64 [upgradable from: 3.7.5-1]
libpython3-stdlib/focal-proposed 3.7.5-1ubuntu1 arm64 [upgradable from: 3.7.5-1]
libseccomp2/focal-proposed 2.4.1-0ubuntu0.19.10.4 arm64 [upgradable from: 2.4.1-0ubuntu0.19.10.3]
linux-headers-generic/focal-proposed 5.3.0.21.24 arm64 [upgradable from: 5.3.0.19.22]
linux-headers-virtual/focal-proposed 5.3.0.21.24 arm64 [upgradable from: 5.3.0.19.22]
linux-image-virtual/focal-proposed 5.3.0.21.24 arm64 [upgradable from: 5.3.0.19.22]
linux-libc-dev/focal-proposed 5.3.0-21.22 arm64 [upgradable from: 5.3.0-19.20]
linux-virtual/focal-proposed 5.3.0.21.24 arm64 [upgradable from: 5.3.0.19.22]
lz4/focal-proposed 1.9.2-1 arm64 [upgradable from: 1.9.1-2]
python3-all-dev/focal-proposed 3.7.5-1ubuntu1 arm64 [upgradable from: 3.7.5-1]
python3-all/focal-proposed 3.7.5-1ubuntu1 arm64 [upgradable from: 3.7.5-1]
python3-apport/focal-proposed 2.20.11-0ubuntu11 all [upgradable from: 2.20.11-0ubuntu9]
python3-colorama/focal-proposed 0.4.1-1 all [upgradable from: 0.3.7-1]
python3-dev/focal-proposed 3.7.5-1ubuntu1 arm64 [upgradable from: 3.7.5-1]
python3-distupgrade/focal-proposed 1:20.04.4 all [upgradable from: 1:20.04.2]
python3-jwt/focal-proposed 1.7.1-2 all [upgradable from: 1.7.1-1]
python3-launchpadlib/focal-proposed 1.10.7-2 all [upgradable from: 1.10.7-1]
python3-lazr.restfulclient/focal-proposed 0.14.2-2 all [upgradable from: 0.14.2-1]
python3-lazr.uri/focal-proposed 1.0.3-4 all [upgradable from: 1.0.3-3]
python3-minimal/focal-proposed 3.7.5-1ubuntu1 arm64 [upgradable from: 3.7.5-1]
python3-oauthlib/focal-proposed 3.1.0-1 all [upgradable from: 2.1.0-1]
python3-pkg-resources/focal-proposed 41.4.0-1 all [upgradable from: 41.1.0-1]
python3-problem-report/focal-proposed 2.20.11-0ubuntu11 all [upgradable from: 2.20.11-0ubuntu9]
python3-twisted-bin/focal-proposed 18.9.0-4 arm64 [upgradable from: 18.9.0-3ubuntu1]
python3-twisted/focal-proposed 18.9.0-4 all [upgradable from: 18.9.0-3ubuntu1]
python3-wadllib/focal-proposed 1.3.3-3 all [upgradable from: 1.3.3-2]
python3/focal-proposed 3.7.5-1ubuntu1 arm64 [upgradable from: 3.7.5-1]
ubuntu-release-upgrader-core/focal-proposed 1:20.04.4 all [upgradable from: 1:20.04.2]

I especially wanted to check linux-libc-dev as that brings the headers used here:

That 5.3.0-19.20 is actually newer and just in the image.
There is a 5.3.0-18.19 from http://us.ports.ubuntu.com/ubuntu-ports focal/main.
So maybe instead of upgrading the trigger is downgrading to that?

Fail: LP build (two days ago): 5.3.0-18.19
Fail: LP build (rebuild today): 5.3.0-18.19
Good: canonistack (focal image): 5.3.0-19.20
Good: canonistack (focal-proposed): 5.3.0-21.22
Good: canonistack (focal-release): 5.3.0-18.19

This isn't very insightful, it just always works except in LP builders :-/
The difference in the package version, even when rebuilding is odd, but at least in the tests wasn't the reason.

For now I'm scratching my head and will hit rebuild tomorrow again ... ?!