Comment 0 for bug 2060213

logfile:
https://objectstorage.prodstack5.canonical.com/swift/v1/AUTH_0f9aae918d5b4744bf7b827671c86842/autopkgtest-noble/noble/armhf/b/balsa/20240404_081820_ad372@/log.gz

pertinent log messages:
```
883s Get:204 http://ftpmaster.internal/ubuntu noble-proposed/universe armhf xvfb armhf 2:21.1.11-2ubuntu2 [738 kB]
935s autopkgtest: WARNING: apt failed to download packages, retrying in 10s...
954s E: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 763 (apt-get)
954s E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), is another process using it?
955s autopkgtest: WARNING: Test dependencies are unsatisfiable - calling apt install on test deps directly for further data about failing dependencies in test logs
957s Reading package lists...
958s Building dependency tree...
```

It perhaps looks like in setup-testbed, whilst sleeping before a retry, another process starts an apt-get command which causes the script to fail after the sleep. Or something along those lines.