No custom logger in library mode

[yarikoptic]

Has 2 commits, but it is the first one which is most important, and its commit message describes it:

Remove custom datalad log handlers while enable library mode

ATM, if there is a root level logger set by Python application, which is a
logical thing to do for an application, then datalad log messages end up
duplicated -- once they are provided by the root level log handler and then by
our very own one. E.g. this script

        import logging

        ## The simplest and documented way to enable logging for a Python app
        logging.basicConfig(level=logging.INFO,
                                                format='%(name)s : %(asctime)s - %(levelname)s - %(message)s')

        # Alternative way to enable some root level logging
        # which surprised me
        #logging.info('This is an info message')

        import datalad.support.gitrepo as r

        r.lgr.info("datalad logger talking")

        datalad_lgr = logging.getLogger("datalad")

        print(f"logging has handlers: {logging.getLogger().handlers}")
        print(f"DataLad has handlers: {datalad_lgr.handlers}"

would produce following output:

    ❯ python simplest_app2.py
    [INFO   ] datalad logger talking
    datalad.gitrepo : 2023-10-24 16:27:02,703 - INFO    - datalad logger talking
    logging has handlers: [<StreamHandler <stderr> (NOTSET)>]
    DataLad has handlers: [<ProgressHandler (NOTSET)>]

so you see our log line duplicated! With the proposed change, we will
explicitly remove all assigned handlers when enabling library mode, and
if we add to above script the datalad.enable_librarymode() we get

    ❯ python simplest_app2.py
    datalad.gitrepo : 2023-10-24 16:29:25,478 - INFO - datalad logger talking
    logging has handlers: [<StreamHandler <stderr> (NOTSET)>]
    DataLad has handlers: []

We also have to respect config variable so we could handle properly the
DATALAD_RUNTIME_LIBRARYMODE environment variable.

edit 1: also it is likely to "interfere" in setting the level unconditionally ATM, I think the set_level is invoked and that results in changing the level here even though root logger might already be set some other level by "main library". I am leaning toward RFing this PR as doing our custom logger overall only when setting to "cmdline" mode.

TODOs:

• decide to may be to position against maint???
• decide to may be go more drastic: no custom logging handling unless in CLI or somehow explicitly instructed

[codeclimate]

Code Climate has analyzed commit 165a3a9 and detected 1 issue on this pull request.

Here's the issue category breakdown:

Category	Count
Complexity	1

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (1d4ff45) 91.59% compared to head (165a3a9) 91.34%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7521      +/-   ##
==========================================
- Coverage   91.59%   91.34%   -0.25%     
==========================================
  Files         325      325              
  Lines       43427    43435       +8     
  Branches     5821     5824       +3     
==========================================
- Hits        39777    39676     -101     
- Misses       3635     3744     +109     
  Partials       15       15              

Files	Coverage Δ
datalad/__init__.py	78.57% <100.00%> (-3.79%)	⬇️
datalad/cli/main.py	82.00% <100.00%> (ø)
datalad/log.py	82.69% <100.00%> (-6.03%)	⬇️

... and 26 files with indirect coverage changes

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[mih]

I am not sure if this is a sensible thing to do. I believe it would turn of any progress reporting also.

I am not familiar with what a library is supposed to do for logging, so I cannot be helpful here. However, I understand the desire to turn off datalad's logging verbosity.

[yarikoptic]

I am not sure if this is a sensible thing to do. I believe it would turn of any progress reporting also.

Indeed worth checking would happen to them!