Error reading SSH protocol banner during `reboot` on Ubuntu 24.04

[amrishparmar]

When attempting to run the reboot command on Ubuntu 24.04, it results in a series of exceptions.

I won't post the full trace as it's very long and they seem to end up in bit of a loop anyway, but relevant sections include

Traceback (most recent call last):
  File "/home/amrish/miniconda3/envs/myenv/lib/python3.12/site-packages/paramiko/transport.py", line 2363, in _check_banner
    buf = self.packetizer.readline(timeout)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/amrish/miniconda3/envs/myenv/lib/python3.12/site-packages/paramiko/packet.py", line 395, in readline
    buf += self._read_timeout(timeout)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/amrish/miniconda3/envs/myenv/lib/python3.12/site-packages/paramiko/packet.py", line 665, in _read_timeout
    raise EOFError()
EOFError

Traceback (most recent call last):
  File "/home/amrish/miniconda3/envs/myenv/lib/python3.12/site-packages/paramiko/transport.py", line 2179, in run
    self._check_banner()
  File "/home/amrish/miniconda3/envs/myenv/lib/python3.12/site-packages/paramiko/transport.py", line 2367, in _check_banner
    raise SSHException(
paramiko.ssh_exception.SSHException: Error reading SSH protocol banner

fabric.exceptions.NetworkError: Error reading SSH protocol banner

Other commands (like run) seem to behave fine.

Potentially also affects other new-ish versions of Ubuntu, but I haven't tried to test with those. This issue doesn't happen on older versions of Ubuntu (e.g. 22.04)

Minimal reproduction:

1. Set up a remote server running Ubuntu 24.04 that you have SSH access to
2. Create the following file

  from fabric.api import env, reboot, run, task
  
  env.host_string = "myserver.example.com"
  env.user = "myuser"
  
  @task
  def test_reboot():
      run("echo 'Rebooting server...'")
      reboot()

3. Run fab test_reboot

Versions:

➜  fab --version                  
fab-classic 1.20.1
Paramiko 4.0.0
Python 3.12.8

I first encountered this a while ago (at least as far back as Jan '25), so don't think it's related to any recent releases of fab-classic or Paramiko.