anchor.diff:  /// [omit]
   let buildArgs (param: NugetInstallParams) =
       [   param.Sources |> argList "source"
  -        (match param.Version with | Some version -> sprintf "-version \"%s\"" version | _ -> "")
  +        (if param.Version <> "" then sprintf "-version \"%s\""  param.Version else "")
           (if param.OutputDirectory <> "" then sprintf "-outputdirectory \"%s\"" param.OutputDirectory else "")
           (match param.Verbosity with | Quiet -> "quiet" | Detailed -> "detailed" | Normal -> "")
           (if param.ExcludeVersion then "-excludeversion" else "")
  
positive.code:       TimeOut = TimeSpan.FromMinutes 5.
        Retries = 5
        Sources = []
        Version = None
        ExcludeVersion = false
        OutputDirectory = "./packages/"
        Prerelease = false
  
negative.code:       /// Nuget feeds to search updates in. Use default if empty.
        Sources: string list
        /// The version of the package to install.
        Version: string
        /// If set, the destination directory will contain only the package name, not the version number. Default `false`.
        ExcludeVersion: bool
        /// Allows updating to prerelease versions. Default `false`.
  