pyinfra/connectors: Fix overwriting of users known_hosts file (#1209)

[evoldstad]

This fixes issue #1209, making it so that we append new keys to the users known_hosts file instead of overwriting it.

Additionally:

• Added a testcase that should discover this breaking in the future
• Broke out the append functionality into a "append_hostkey" function, making it so we don't needlessly reuse code for AskPolicy
• Linting actually correct this time.
• Merged commits correctly this time.

Previous behaviour when adding a new

• Create a paramiko.HostKeys object
• Read the users known_hosts file
• Add the new key to the paramiko object.
• Save the object, overwriting the users host_keys file without comments and entries incompatible with paramiko.

New behaviour:

• Create a paramiko.HostKeyEntry object using the new hostname and
  corresponding key.
• Append this key to the existing known_hosts file.

[evoldstad]

The spelling issue seems to be a false positive, as it reacts on a part of the example key used in the test. Any way to override this behaviour, or mark it as a non-issue?

[simonhammes]

The spelling issue seems to be a false positive, as it reacts on a part of the example key used in the test. Any way to override this behaviour, or mark it as a non-issue?

You can either ignore the whole file or ignore certain expressions based on regular expressions: https://github.com/pyinfra-dev/pyinfra/blob/3.x/.typos.toml

[evoldstad]

The spelling issue seems to be a false positive, as it reacts on a part of the example key used in the test. Any way to override this behaviour, or mark it as a non-issue?

You can either ignore the whole file or ignore certain expressions based on regular expressions: https://github.com/pyinfra-dev/pyinfra/blob/3.x/.typos.toml

Thanks, that fixed it!

[Fizzadar]

Amazing, thank you for fixing this @evoldstad!