RF: use parse_known_args instead of _parse_known_args

[yarikoptic]

parse_known_args seems to be doing some processing which we did not
apparently needed. @mih raised concern/question on why we use protected
method and there were no comment/rationale left in the code.

I have set exit_on_error to False since we do not want to add that
error handling behavior since we did not rely on it before

Timing on my laptop on this commit

$> multitime -n 5 datalad --help-np 1>/dev/null
===> multitime results
1: datalad --help-np
			Mean        Std.Dev.    Min         Median      Max
real        1.304       0.026       1.276       1.294       1.353
user        1.232       0.035       1.197       1.221       1.300
sys         0.076       0.010       0.057       0.080       0.085

and on master

$> multitime -n 5 datalad --help-np 1>/dev/null
===> multitime results
1: datalad --help-np
			Mean        Std.Dev.    Min         Median      Max
real        1.312       0.037       1.270       1.315       1.365
user        1.229       0.032       1.184       1.228       1.265
sys         0.087       0.012       0.072       0.090       0.106

so no notable negative impact (good).

🏠 Internal

• Use public ArgumentParser.parse_known_args instead of protected _parse_known_args

[yarikoptic]

aha -- failures against extensions shine the light on "why/whatfor":

Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.[7](https://github.com/datalad/datalad/runs/5053410484?check_suite_focus=true#step:11:7).12/x64/bin/datalad", line [8](https://github.com/datalad/datalad/runs/5053410484?check_suite_focus=true#step:11:8), in <module>
    sys.exit(main())
  File "/opt/hostedtoolcache/Python/3.7.12/x64/lib/python3.7/site-packages/datalad/cli/main.py", line 74, in main
    parser = setup_parser(args, completing="_ARGCOMPLETE" in os.environ)
  File "/opt/hostedtoolcache/Python/3.7.12/x64/lib/python3.7/site-packages/datalad/cli/parser.py", line [10](https://github.com/datalad/datalad/runs/5053410484?check_suite_focus=true#step:11:10)4, in setup_parser
    exit_on_error=False,
TypeError: __init__() got an unexpected keyword argument 'exit_on_error'
Error: Process completed with exit code 1.

looking at http://github.com/python/cpython/blob/HEAD/Doc/library/argparse.rst

   .. versionchanged:: 3.9
      *exit_on_error* parameter was added.

so we could do the switch starting from 3.9. I will add a commit reverting this RF and adding a comment to do whenever 3.9 is minimal version.

[codeclimate]

Code Climate has analyzed commit 03645e5 and detected 0 issues on this pull request.

View more on Code Climate.

[yarikoptic]

@jwodder is there a way to instruct auto to not bother about changelog entry at all for a PR?

[jwodder]

@yarikoptic I don't think so.

[codecov]

Codecov Report

Merging #6414 (03645e5) into master (cc84266) will increase coverage by 0.43%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #6414      +/-   ##
==========================================
+ Coverage   89.57%   90.01%   +0.43%     
==========================================
  Files         345      345              
  Lines       43032    43312     +280     
==========================================
+ Hits        38545    38986     +441     
+ Misses       4487     4326     -161     

Impacted Files	Coverage Δ
datalad/cli/parser.py	84.76% <ø> (+0.47%)	⬆️
datalad/_version.py	46.99% <0.00%> (-53.01%)	⬇️
datalad/customremotes/tests/test_archives.py	89.28% <0.00%> (-0.65%)	⬇️
datalad/support/tests/test_annexrepo.py	97.97% <0.00%> (+0.13%)	⬆️
datalad/support/gitrepo.py	90.37% <0.00%> (+0.16%)	⬆️
datalad/distribution/tests/test_install.py	100.00% <0.00%> (+0.20%)	⬆️
datalad/distribution/tests/test_dataset.py	99.70% <0.00%> (+0.29%)	⬆️
datalad/core/distributed/tests/test_clone.py	97.57% <0.00%> (+0.36%)	⬆️
datalad/local/add_archive_content.py	88.03% <0.00%> (+0.42%)	⬆️
datalad/support/network.py	87.22% <0.00%> (+0.44%)	⬆️
... and 40 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update cc84266...03645e5. Read the comment docs.

[mih]

Thx for the investigation and leaving this note!