fix: windows core count from powershell

[maxnbk]

Closes #2029 .

Explanation:

wmic was removed as a default install in Windows 11 24H2, causing rez to fail at startup when physical core count is computed.

Fix:

Replace it with a PowerShell/Get-CimInstance equivalent - powershell.exe (Windows PowerShell 5.1) ships with all Windows 10/11 installs and is guaranteed available. The old wmic path is retained as a fallback for older Windows builds.

Disclosure:

This PR was AI-assisted with Claude Code, Sonnet 4.6, primarily for diagnostics, logic-tracing, documentation and edge-case verification.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.69%. Comparing base (d415b96) to head (f92b52e).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2108      +/-   ##
==========================================
+ Coverage   60.65%   60.69%   +0.04%     
==========================================
  Files         164      164              
  Lines       20584    20598      +14     
  Branches     3579     3580       +1     
==========================================
+ Hits        12485    12502      +17     
+ Misses       7224     7220       -4     
- Partials      875      876       +1     

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[JeanChristopheMorinPerso]

Suggested change

import subprocess

subprocess is already imported at the top level.

[Copilot]

Pull request overview

This PR addresses Windows 11 24H2 environments where wmic is no longer present by updating Rez’s Windows physical core detection to prefer a PowerShell/CIM-based query, while retaining wmic as a fallback for older Windows builds.

Changes:

• Added WindowsPlatform._physical_cores_from_powershell() using Get-CimInstance/Measure-Object and updated _physical_cores() to prefer it before falling back to WMIC.
• Clarified WMIC helper intent as a fallback for older Windows versions.
• Added Windows-only unit tests covering PowerShell/WMIC parsing and the fallback chain, plus basic smoke checks for logical_cores/physical_cores.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/rez/utils/platform_.py	Adds PowerShell-based physical core detection and prefers it over WMIC with WMIC retained as fallback.
src/rez/tests/test_utils.py	Adds Windows-only tests for the new PowerShell core counting helper and fallback behavior.

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