mono/mono — pull request #1154 by Zoltu (2014-07-10 04:45:49+00:00)
Title: Makes AppendTextUnquoted public.

The Microsoft version is public, so should this be.
NuGet.MSBuild.Tools.CommandLineBuilderExtensions:AppendTextUnquotedIfNotNullOrEmpty attempts to call this method in NuGet for MSBuild NuGet package.