The following BasicCompilerSemanticTest unit tests fail when run under the es-ES locale:

• Microsoft.CodeAnalysis.VisualBasic.UnitTests.CompilationAPITests.EmitOptionsDiagnostics
  Message

  Expected:
      Diagnostic(ERRID.ERR_InvalidDebugInformationFormat).WithArguments(\"-1\"),
      Diagnostic(ERRID.ERR_InvalidOutputName).WithArguments(\"El nombre no puede empezar con un espacio en blanco.\"),
      Diagnostic(ERRID.ERR_InvalidFileAlignment).WithArguments(\"513\"),
      Diagnostic(ERRID.ERR_InvalidSubsystemVersion).WithArguments(\"1000000.-1000000\"),
      Diagnostic(ERRID.ERR_InvalidHashAlgorithmName).WithArguments(\"invalid hash algorithm name\")
  Actual:
      Diagnostic(ERRID.ERR_InvalidDebugInformationFormat).WithArguments(\"-1\").WithLocation(1, 1),
      Diagnostic(ERRID.ERR_InvalidOutputName).WithArguments(\"Name cannot start with whitespace.\").WithLocation(1, 1),
      Diagnostic(ERRID.ERR_InvalidFileAlignment).WithArguments(\"513\").WithLocation(1, 1),
      Diagnostic(ERRID.ERR_InvalidSubsystemVersion).WithArguments(\"1000000.-1000000\").WithLocation(1, 1),
      Diagnostic(ERRID.ERR_InvalidHashAlgorithmName).WithArguments(\"invalid hash algorithm name\").WithLocation(1, 1)
  Diff:
          Diagnostic(ERRID.ERR_InvalidDebugInformationFormat).WithArguments(\"-1\"),
  ++>     Diagnostic(ERRID.ERR_InvalidOutputName).WithArguments(\"Name cannot start with whitespace.\").WithLocation(1, 1),
  -->     Diagnostic(ERRID.ERR_InvalidOutputName).WithArguments(\"El nombre no puede empezar con un espacio en blanco.\"),
          Diagnostic(ERRID.ERR_InvalidFileAlignment).WithArguments(\"513\"),
          Diagnostic(ERRID.ERR_InvalidSubsystemVersion).WithArguments(\"1000000.-1000000\"),
          Diagnostic(ERRID.ERR_InvalidHashAlgorithmName).WithArguments(\"invalid hash algorithm name\")
  Expected: True
  Actual:   False
  

  Stack trace:

   en Xunit.Assert.True(Nullable`1 condition, String userMessage)
   en Xunit.Assert.True(Boolean condition, String userMessage)
   en Microsoft.CodeAnalysis.DiagnosticExtensions.Verify(IEnumerable`1 actual, DiagnosticDescription[] expected, Boolean errorCodeOnly)
   en Microsoft.CodeAnalysis.DiagnosticExtensions.Verify(IEnumerable`1 actual, DiagnosticDescription[] expected)
   en Microsoft.CodeAnalysis.DiagnosticExtensions.Verify(ImmutableArray`1 actual, DiagnosticDescription[] expected)
   en Microsoft.CodeAnalysis.VisualBasic.UnitTests.CompilationAPITests.EmitOptionsDiagnostics()
  

Full details in Roslyn.Compilers.VisualBasic.Semantic.UnitTests.dll.zip