Output all logging to stderr (#353)

[georgek]

Outputs all logging stuff to stderr which fixes a number of current open issues including #353 and #275.

Note that this breaks the existing CLI. Namely, if anyone is relying on the fact that stuff comes out of standard output and redirecting it somewhere. They shouldn't be, but someone probably is.

One liner: Output all logging to stderr instead of stdout

Contributor checklist

• Provided the tests for the changes.
• Requested a review from another contributor.
• Gave a clear one-line description in the PR (that the maintainers can add to CHANGELOG.md on release).
• Assign the PR to an existing or new milestone for the target version (following Semantic Versioning).

[atugushev]

I would gladly merge this.

@vphilippon what do you think? Should we take advantage of semver and release it under 4.0.0?

[atugushev]

LGTM 👍

[auvipy]

Please re base

[codecov]

Codecov Report

Merging #834 into master will decrease coverage by 0.07%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #834      +/-   ##
==========================================
- Coverage   98.76%   98.68%   -0.08%     
==========================================
  Files          36       36              
  Lines        2193     2137      -56     
  Branches      285      279       -6     
==========================================
- Hits         2166     2109      -57     
  Misses         16       16              
- Partials       11       12       +1

Impacted Files	Coverage Δ
piptools/logging.py	100% <100%> (ø)	⬆️
tests/test_cli_compile.py	100% <100%> (ø)	⬆️
tests/test_cli_sync.py	100% <100%> (ø)	⬆️
tests/conftest.py	94.44% <100%> (-2.82%)	⬇️
piptools/exceptions.py	86.11% <0%> (-3.37%)	⬇️
piptools/resolver.py	100% <0%> (ø)	⬆️
piptools/utils.py	100% <0%> (ø)	⬆️
tests/test_resolver.py	100% <0%> (ø)	⬆️
... and 1 more

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[codecov]

Codecov Report

Merging #834 into master will decrease coverage by 0.07%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #834      +/-   ##
==========================================
- Coverage   98.76%   98.68%   -0.08%     
==========================================
  Files          36       36              
  Lines        2193     2137      -56     
  Branches      285      279       -6     
==========================================
- Hits         2166     2109      -57     
  Misses         16       16              
- Partials       11       12       +1

Impacted Files	Coverage Δ
piptools/logging.py	100% <100%> (ø)	⬆️
tests/test_cli_compile.py	100% <100%> (ø)	⬆️
tests/test_cli_sync.py	100% <100%> (ø)	⬆️
tests/conftest.py	94.44% <100%> (-2.82%)	⬇️
piptools/exceptions.py	86.11% <0%> (-3.37%)	⬇️
piptools/resolver.py	100% <0%> (ø)	⬆️
piptools/utils.py	100% <0%> (ø)	⬆️
tests/test_resolver.py	100% <0%> (ø)	⬆️
... and 1 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 01d5c09...d2bbbc0. Read the comment docs.

[georgek]

Rebased and added a couple of examples to the README which cleans up several issues: #275 #353 #360 #362

[atugushev]

pip-tools v3.9.0 is released.