msbuild: InvalidOperationException from TaskLoggingHelper.FormatResourceString(): The "Csc" task has not registered its resources.

Building using bootstrap MSBuild from 80b7f2dcb has resulted in a Csc failure:

Csc
    Assembly = C:\msbuild\artifacts\bin\bootstrap\net472\MSBuild\Current\Bin\Roslyn\Microsoft.Build.Tasks.CodeAnalysis.dll
C:\msbuild\artifacts\bin\bootstrap\net472\MSBuild\Current\Bin\Roslyn
    Microsoft (R) Visual C# Compiler version 3.9.0-2.20574.26 (e9fd4dc7)
    Errors
        C:\msbuild\artifacts\bin\bootstrap\net472\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(71,5): error MSB4018: The "Csc" task failed unexpectedly.
This is an unhandled exception from a task -- PLEASE OPEN A BUG AGAINST THE TASK OWNER.
System.InvalidOperationException: The "Csc" task has not registered its resources. In order to use the "TaskLoggingHelper.FormatResourceString()" method this task needs to register its resources either during construction, or via the "TaskResources" property.
   at Microsoft.Build.Shared.ErrorUtilities.ThrowInvalidOperation(String resourceName, Object[] args) in C:\msbuild\src\Shared\ErrorUtilities.cs:line 327
   at Microsoft.Build.Shared.ErrorUtilities.VerifyThrowInvalidOperation(Boolean condition, String resourceName, Object arg0) in C:\msbuild\src\Shared\ErrorUtilities.cs:line 368
   at Microsoft.Build.Utilities.TaskLoggingHelper.FormatResourceString(String resourceName, Object[] args) in C:\msbuild\src\Shared\TaskLoggingHelper.cs:line 203
   at Microsoft.Build.Utilities.TaskLoggingHelper.LogErrorWithCodeFromResources(String subcategoryResourceName, String file, Int32 lineNumber, Int32 columnNumber, Int32 endLineNumber, Int32 endColumnNumber, String messageResourceName, Object[] messageArgs) in C:\msbuild\src\Shared\TaskLoggingHelper.cs:line 825
   at Microsoft.Build.Utilities.TaskLoggingHelper.LogErrorWithCodeFromResources(String messageResourceName, Object[] messageArgs) in C:\msbuild\src\Shared\TaskLoggingHelper.cs:line 779
   at Microsoft.CodeAnalysis.BuildTasks.ManagedCompiler.ExecuteTool(String pathToTool, String responseFileCommands, String commandLineCommands)
   at Microsoft.Build.Utilities.ToolTask.Execute() in C:\msbuild\src\Utilities\ToolTask.cs:line 1519
   at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute() in C:\msbuild\src\Build\BackEnd\TaskExecutionHost\TaskExecutionHost.cs:line 578
   at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext() in C:\msbuild\src\Build\BackEnd\Components\RequestBuilder\TaskBuilder.cs:line 809 [C:\Ide\src\CodexShell\CodexShell.csproj]