Comment 2 for bug 1885164

Tail of the log for a failed build (full log attached):

Err libavahi-glib1_0.7-4ubuntu7.1_arm64.deb

  407 Proxy Authentication Required [IP: 10.10.10.1 8222]

Fetched 0 B in 0s (0 B/s)
Package fetch error: The item '/root/.cache/snapcraft/download/libavahi-glib1_0.7-4ubuntu7.1_arm64.deb' could not be fetched: 407 Proxy Authentication Required [IP: 10.10.10.1 8222]
Build failed
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/lpbuildd/target/build_snap.py", line 222, in run
    self.pull()
  File "/usr/lib/python3/dist-packages/lpbuildd/target/build_snap.py", line 192, in pull
    env=env)
  File "/usr/lib/python3/dist-packages/lpbuildd/target/build_snap.py", line 100, in run_build_command
    return self.backend.run(args, env=full_env, **kwargs)
  File "/usr/lib/python3/dist-packages/lpbuildd/target/lxd.py", line 537, in run
    subprocess.check_call(cmd, **kwargs)
  File "/usr/lib/python3.6/subprocess.py", line 311, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['lxc', 'exec', 'lp-focal-arm64', '--env', 'LANG=C.UTF-8', '--env', 'SHELL=/bin/sh', '--env', 'http_proxy=http://10.10.10.1:8222/', '--env', 'https_proxy=http://10.10.10.1:8222/', '--env', 'GIT_PROXY_COMMAND=/usr/local/bin/lpbuildd-git-proxy', '--env', 'SNAPPY_STORE_NO_CDN=1', '--env', 'SNAPCRAFT_LOCAL_SOURCES=1', '--env', 'SNAPCRAFT_SETUP_CORE=1', '--env', 'SNAPCRAFT_BUILD_INFO=1', '--env', 'SNAPCRAFT_IMAGE_INFO={"build-request-id": "lp-67760438", "build-request-timestamp": "2021-12-03T12:19:48Z", "build_url": "https://launchpad.net/~saviq/+snap/snapcraft-wpe-webkit-mir-kiosk-e08b19bacdf39f81c2d161436f172dfd/+build/1600431"}', '--env', 'SNAPCRAFT_BUILD_ENVIRONMENT=host', '--', '/bin/sh', '-c', 'cd /build/snapcraft-wpe-webkit-mir-kiosk-e08b19bacdf39f81c2d161436f172dfd && linux64 snapcraft pull']' returned non-zero exit status 2.
Revoking proxy token...
Unable to revoke token for SNAPBUILD-1600431-1638533990: HTTP Error 401: UnauthorizedRUN: /usr/share/launchpad-buildd/bin/in-target scan-for-processes --backend=lxd --series=focal --arch=arm64 SNAPBUILD-1600431
Scanning for processes to kill in build SNAPBUILD-1600431