Try arping as last resort

[scop]

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Code changes:

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  • black getmac tests
• Are the linting checks passing?
  • tox -e check -- no, but they weren't passing before this change either:

check run-test: commands[3] | flake8 getmac tests setup.py
getmac/getmac.py:1:1: T499 Success: no issues found in 1 source file
# -*- coding: utf-8 -*-
^
ERROR: InvocationError for command [...]/getmac/.tox/check/bin/flake8 getmac tests setup.py (exited with code 1)

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Summary of changes:

When other things have yielded no results, try arping. Depending on system, it may require an interface to be specified and fail without one, but would improve things where it doesn't.

[GhostofGoes]

This looks great, thank you! Hopefully this helps fix the problem in the mentioned issue (or at least avoid related issues in the future)!

[GhostofGoes]

Will try to get this released on PyPI as 0.8.2 by this Saturday

[scop]

Thanks! Turns out it doesn't immediately seem to fix the problem, but I believe it's a good addition to have in getmac anyway.

Alas, I've learned that the https://github.com/ThomasHabets/arping arping implementation doesn't support the -f option, and its output differs from the iputils/busybox arping somewhat as well. So for now this implementation doesn't work with the ThomasHabets one -- I'll see if I can get the -f option supported there too, as well as submit a followup PR here to recognize its output. (The -f could in theory be dropped, but it makes the call a bit faster, so I think it's good to keep it.)