Comment 1 for bug 1900852

disabling `uart1` leads to `cloud-init` failures when writing keys:

```
2020-10-26 18:37:30,888 - util.py[WARNING]: Running module keys-to-console (<module 'cloudinit.config.cc_keys_to_console' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_keys_to_console.py'>) failed
2020-10-26 18:37:30,889 - util.py[DEBUG]: Running module keys-to-console (<module 'cloudinit.config.cc_keys_to_console' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_keys_to_console.py'>) failed
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/cloudinit/util.py", line 402, in multi_log
    wfh.flush()
OSError: [Errno 5] Input/output error

During handling of the above exception, another exception occurred:

OSError: [Errno 5] Input/output error

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/cloudinit/stages.py", line 848, in _run_modules
    ran, _r = cc.run(run_name, mod.handle, func_args,
  File "/usr/lib/python3/dist-packages/cloudinit/cloud.py", line 54, in run
    return self._runners.run(name, functor, args, freq, clear_on_fail)
  File "/usr/lib/python3/dist-packages/cloudinit/helpers.py", line 185, in run
    results = functor(*args)
  File "/usr/lib/python3/dist-packages/cloudinit/config/cc_keys_to_console.py", line 69, in handle
    util.multi_log("%s\n" % (stdout.strip()),
  File "/usr/lib/python3/dist-packages/cloudinit/util.py", line 402, in multi_log
    wfh.flush()
OSError: [Errno 5] Input/output error

```

We've had discussions regarding default console connections (specifically console=ttyS0) at various points. It appears cloud-init will have this specific issue when no console is connection is available at boot, at least for NoCloud