System.ObjectDisposedException : Cannot write to a closed TextWriter in printf in numerous tests

[brettfo]

We've had several signed test runs fail recently with:

System.ObjectDisposedException : Cannot write to a closed TextWriter.

at System.IO.__Error.WriterClosed()
   at System.IO.StringWriter.Write(String value)
   at System.IO.TextWriter.SyncTextWriter.Write(String value)
   at Microsoft.FSharp.Core.PrintfImpl.clo@1264-14.Invoke(FSharpList`1 _args, FSharpFunc`2 initial) in D:\workspace\_work\1\s\src\fsharp\FSharp.Core\printf.fs:line 1266
   at Scripting.log[a](PrintfFormat`4 format) in D:\workspace\_work\1\s\src\scripts\scriptlib.fsx:line 81
   at TestFramework.logConfig(TestConfig cfg) in D:\workspace\_work\1\s\tests\FSharp.Test.Utilities\TestFramework.fs:line 360
   at TestFramework.initializeSuite() in D:\workspace\_work\1\s\tests\FSharp.Test.Utilities\TestFramework.fs:line 413
   at TestFramework.suiteHelpers@418.Invoke(Unit unitVar) in D:\workspace\_work\1\s\tests\FSharp.Test.Utilities\TestFramework.fs:line 418
   at System.Lazy`1.CreateValue()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Lazy`1.get_Value()
   at TestFramework.testConfig(String testDir) in D:\workspace\_work\1\s\tests\FSharp.Test.Utilities\TestFramework.fs:line 436
   at SingleTest.singleTestBuildAndRun(String dir, Permutation p) in D:\workspace\_work\1\s\tests\fsharp\single-test.fs:line 375
   at FSharp.Tests.Core.singleTestBuildAndRun@35-1.Invoke(String dir, Permutation p) in D:\workspace\_work\1\s\tests\fsharp\tests.fs:line 35
   at FSharp.Tests.Core.GeneratedSignatureTests.innerpoly-GENERATED_SIGNATURE() in D:\workspace\_work\1\s\tests\fsharp\tests.fs:line 3131

There are usually ~500 failures, all with the same stack trace.

[KevinRansom]

@brettfo --- can we close this?

[vzarytovskii]

@KevinRansom happened once to me in net6 branch with your fix merged:
https://dev.azure.com/dnceng/public/_build/results?buildId=1268817&view=logs&j=966222a4-f29d-5ec0-88cc-1b798728906e&t=052eabf8-67e2-5f29-745c-00cc34aa0e02

[KevinRansom]

Fixed by #11917