[Flaky Test] Microsoft.Build.Coordinator.UnitTests.CoordinatorIntegration_Tests.NestedBuild_InheritsCoordinatorGrant_DoesNotDeadlock

**Flaky-test key** (automated de-duplication — do not edit):
```text
flaky-test-id: Microsoft.Build.Coordinator.UnitTests.CoordinatorIntegration_Tests.NestedBuild_InheritsCoordinatorGrant_DoesNotDeadlock
```

## Evidence

- **Distinct sources:** 3 (1 PR + 2 rolling builds)
- **Affected PRs:** [#14470](https://github.com/dotnet/msbuild/pull/14470)
- **Rolling builds:** [1523135](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1523135), [1530976](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1530976)
- **Legs:** CoreOnMac, FullOnWindows Release
- **TFMs:** net11.0
- **Assembly:** Microsoft.Build.Coordinator.UnitTests
- **First seen:** 2026-07-21 | **Last seen:** 2026-07-29

## Sample error

```
Shouldly.ShouldAssertException : buildOutput
should not contain (case insensitive comparison)
"Failed to connect to the build coordinator"
```

## Fully-qualified test name

`Microsoft.Build.Coordinator.UnitTests.CoordinatorIntegration_Tests.NestedBuild_InheritsCoordinatorGrant_DoesNotDeadlock`

Source: `src/MSBuild.Coordinator.UnitTests/CoordinatorIntegration_Tests.cs`

## Next steps

This test will be quarantined via `[ActiveIssue("https://github.com/dotnet/msbuild/issues/")]` (from `Microsoft.DotNet.XUnitV3Extensions`, namespace `Xunit`) until the underlying nondeterminism is fixed. This approach stamps the `Category=failing` trait, which normal CI excludes; the quarantine pipeline (def 344) re-runs it on all platforms to gather ongoing signal.

> [!WARNING]
>
> Firewall blocked 1 domain
>
> The following domain was blocked by the firewall during workflow execution:
>
> - `awmgmcpg`
>> To allow these domains, add them to the `network.allowed` list in your workflow frontmatter:
>
> ```yaml
> network:
> allowed:
> - defaults
> - "awmgmcpg"
> ```
>
> See [Network Configuration](https://github.github.com/gh-aw/reference/network/) for more information.
>
>

> Generated by [Flaky Test Triage](https://github.com/dotnet/msbuild/actions/runs/30451703648) · sonnet46 · 150.7 AIC · ⌖ 5.46 AIC · ⊞ 14.7K · [◷](https://github.com/search?q=repo%3Adotnet%2Fmsbuild+is%3Aissue+%22gh-aw-workflow-call-id%3A+dotnet%2Fmsbuild%2Fflaky-test-detector.agent%22&type=issues)

Start with src/MSBuild.Coordinator.UnitTests/CoordinatorIntegration_Tests.cs and the test Microsoft.Build.Coordinator.UnitTests.CoordinatorIntegration_Tests.NestedBuild_InheritsCoordinatorGrant_DoesNotDeadlock. Reproduce the failure on the CoreOnMac and FullOnWindows Release legs, using the reported coordinator connection error as the signal. Done means the nondeterminism is fixed and the test no longer needs the ActiveIssue quarantine.

Written by the indexing model from the issue text.