[ Reason ]
auto-apt-proxy is a helper tool for APT that automatically detects APT
proxies on the local network. In some networking configurations it might
enter an infinite loop. This bug is

[ Impact ]
auto-apt-proxy might not only not detect a proxy, but will also go into
a infinite loop and prevent APT from working entirely.

[ Tests ]
All the autopkgtest pass with this change. The bug reporter also
confirmed that the change fixes things for them.

[ Risks ]
The change is trivial and risk is minimal, if not zero.

[ Checklist ]
  [x] *all* changes are documented in the d/changelog
  [x] I reviewed all changes and I approve them
  [x] attach debdiff against the package in (old)stable
  [x] the issue is verified as fixed in unstable

[ Changes ]
The call to `apt-helper download-file` will now receive an extra option
telling it to not use an APT proxy autodetection command, which would
cause auto-apt-proxy to be called again.

There is also a change to one of the test cases that is currently
failing in trixie. That test case is not a problem for forky because
there the default timeout for network operations has been changed to 1s
instead of 5.

[ Other info ]
n/a

Sorry this sentence was left incomplete. I meant to say that this is bug
#1142542.

Additionally, I would like to include a second patch, that causes
auto-apt-proxy to wait for the network to be online. In some use cases,
such as in Debian CI (ci.debian.net), apt might be used right away after
the machine starts, and that sometimes means even before the network is
configured, causing excessive use of external connectivity which is
limited for those hosts (and thus why we need to use a proxy on them).
This change uses that same mechanism that apt-daily.service uses, which
is `apt-helper wait-online`.

Please find attached an update diff WRT the version currently in trixie.

Everything else in the original report still applies.