[ci-scan] Skip StartDetached_GrandchildSurvivesSignalingParent on Windows (refs #126936)

[github-actions]

Reasoning

The test System.Diagnostics.Tests.ProcessTests.StartDetached_GrandchildSurvivesSignalingParent(enable: False) has been flaking consistently on Windows in the runtime-extra-platforms pipeline. KBE #126936 confirms 23 hits in the past month and 5 in the past 7 days. The test is assigned to @adamsitnik for investigation. Adding [ActiveIssue] on TestPlatforms.Windows to unblock CI while the root cause is addressed.

The chosen attribute is scoped to Windows only, matching the observed failure scope.

KBE verification:

1. Same test: Yes - StartDetached_GrandchildSurvivesSignalingParent(enable: False)
2. Same failure signature: Yes - Assert.Equal() Failure: Values differ
3. Same OS: Yes - Windows
4. Same architecture: Yes - x64

Impact on platforms

• runtime-extra-platforms / windows-x64 Release Libraries_Release_CoreCLR / Windows.10.Amd64.Open / exit code 1

Errors log

System.Diagnostics.Tests.ProcessTests.StartDetached_GrandchildSurvivesSignalingParent(enable: False) [FAIL]
  Assert.Equal() Failure: Values differ
  Expected: False
  Actual:   True

First build it occurred

KBE #126936 was filed 2026-04-15; Build Analysis shows continuous matches since then (23 hits in 1 month). This is within the scanned window and may not be the true origin.

Linked issue

Linked KBE: #126936

Note

🔒 Integrity filter blocked 1 item

The following item was blocked because it doesn't meet the GitHub integrity level.

• #125825 search_issues: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".

To allow these resources, lower min-integrity in your GitHub frontmatter:

tools:
  github:
    min-integrity: approved  # merged | approved | unapproved | none

Generated by CI Outer-Loop Failure Scanner · ● 37.5M · ◷

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-diagnostics-process
See info in area-owners.md if you want to be subscribed.

[Copilot]

Pull request overview

This PR temporarily disables a flaky System.Diagnostics.Process test on Windows by marking the affected theory with an [ActiveIssue] attribute, preventing it from running on Windows CI while the underlying issue is investigated.

Changes:

• Added [ActiveIssue(..., TestPlatforms.Windows)] to StartDetached_GrandchildSurvivesSignalingParent(...) to skip it on Windows.

Show a summary per file

File	Description
src/libraries/System.Diagnostics.Process/tests/ProcessTests.cs	Skips StartDetached_GrandchildSurvivesSignalingParent on Windows via [ActiveIssue] to mitigate CI flakiness.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 1