Merge fabric3 into v1 mainline

[bitprophet]

Per discussion on the mailing list with @mathiasertl and others. See also my roadmap.

This is purely for the benefit of users still soldiering away on Python 2 + Fabric 1, who'd rather upgrade their dev/deploy systems to Python 3 first instead of jumping to the Fabric 2 API right away. Our primary focus remains on Fabric 2 (and its constituent libraries, Invoke and Paramiko).

This is expected to be the last set of commits to v1 unless severe bugs are discovered.

[arnimarj]

I'm one of those still toiling away with a mix of fabric3 and fabric2, and I'm aware of one issue with fabric3:

$ fab
Traceback (most recent call last):
  File "/home/arni/.config/dohop/tools_venv3/bin/fab", line 5, in <module>
    from fabric.main import main
  File "/home/arni/.config/dohop/tools_venv3/lib/python3.10/site-packages/fabric/main.py", line 12, in <module>
    from collections import Mapping
ImportError: cannot import name 'Mapping' from 'collections' (/home/arni/.pyenv/versions/3.10.3/lib/python3.10/collections/__init__.py)

Changing the import line to from collections.abc import Mapping fixes it

EDIT:

Looking at the documentation from https://docs.python.org/3.5/library/collections.abc.html through to https://docs.python.org/3.9/library/collections.abc.html collections.abc.Mapping seems to exist in all Python versions 3.5+.

[bitprophet]

Nice, thanks @arnimarj ! Guess that's because it was officially removed in 3.10 and a test dependency of ours dies at/after 3.9 so I wasn't able to add 3.9/3.10 to the test matrix. I'll make that fix now...ok, needs a somewhat newer six, unlikely to be an issue. Pushing that fix now.

EDIT: right, so I can't prove everything is great on 3.10 because - no tests - but I was able to do a basic fab -H user@remotehost -- whoami in a vanilla Python 3.10 container, and that worked fine, so the critical path at least has no import errors.

[arnimarj]

Just tried the same my scripts and indeed it works! Thank you for this effort

[un33k]

How to get this change in from pypi?

Use newer six for collections_abc so Python 3.10 might work

It seems after 8 months, the change is still missing from Fabric3==1.14.post1