Fix a bug where pip-compile setup.py would fail due to URL dependency

[atugushev]

Fixes #1346.

Changelog-friendly one-liner: Fix a bug where pip-compile setup.py would fail with URL deps.

Contributor checklist

• Provided the tests for the changes.
• 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 #1347 (d05be7a) into master (fe6dd97) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1347      +/-   ##
==========================================
- Coverage   99.65%   99.65%   -0.01%     
==========================================
  Files          33       33              
  Lines        2883     2882       -1     
  Branches      309      309              
==========================================
- Hits         2873     2872       -1     
  Misses          5        5              
  Partials        5        5              

Impacted Files	Coverage Δ
piptools/scripts/compile.py	100.00% <100.00%> (ø)
tests/test_cli_compile.py	100.00% <100.00%> (ø)

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[auvipy]

nstall_req_from_line() seems good solution. approving from my side. others should check

[atugushev]

Thanks @auvipy 🙏🏼

[astrojuanlu]

I remember struggling for hours to understand the difference between these two functions, and it seems that I still didn't fully get them... thanks @atugushev 👍🏽