Fix replacing password to asterisks in pip-compile

[atugushev]

Fixes #801

Changelog-friendly one-liner: Fix replacing password to asterisks in pip-compile.

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).

[codecov]

Codecov Report

Merging #808 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #808      +/-   ##
==========================================
+ Coverage   98.77%   98.78%   +<.01%     
==========================================
  Files          35       35              
  Lines        2044     2050       +6     
  Branches      262      262              
==========================================
+ Hits         2019     2025       +6     
  Misses         15       15              
  Partials       10       10

Impacted Files	Coverage Δ
piptools/utils.py	100% <100%> (ø)	⬆️
tests/test_utils.py	100% <100%> (ø)	⬆️

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

Codecov Report

Merging #808 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #808      +/-   ##
==========================================
+ Coverage   98.77%   98.78%   +<.01%     
==========================================
  Files          35       35              
  Lines        2044     2050       +6     
  Branches      262      262              
==========================================
+ Hits         2019     2025       +6     
  Misses         15       15              
  Partials       10       10

Impacted Files	Coverage Δ
piptools/utils.py	100% <100%> (ø)	⬆️
tests/test_utils.py	100% <100%> (ø)	⬆️

---

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 8a1a8ef...e203f64. Read the comment docs.