Unit test Microsoft.AspNet.Html.Abstractions.Test.HtmlContentBuilderExtensionsTest.Builder_AppendFormat_WithDifferentCurrentCulture fails on CoreCLR on Linux

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Assert.Equal() Failure
                            ↓ (pos 12)
      Expected: HtmlEncode[[01 February 2015]]
      Actual:   HtmlEncode[[Sunday, 1 February 2015]]
                            ↑ (pos 12)
      Stack Trace:
           at Microsoft.AspNet.Html.Abstractions.Test.HtmlContentBuilderExtensionsTest.Builder_AppendFormat_WithDifferentCurrentCulture()
           at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
           at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
           at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)

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This affects aspnet/Universe#304.

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Opened CoreCLR issue https://github.com/dotnet/corefx/issues/3974