Conflict when adding a nuget to the Test Project

[gusty]

Description

Adding a nuget to the Test project using paket fails due to a conflict of FSharp.Core versions

Repro steps

1. After cloning, run build as stated in the doc, name the solution MySolution, put anything for the rest.

2. Go to the paket directory and add a nuget to the Test group like this:

   paket add project MySolution.Tests group Test nuget YC.PrettyPrinter

Expected behavior

Succeed

Actual behavior

Fails with this error:

Package FSharp.Core is referenced in different versions in C:\ProjectScaffold\tests\MySolution.Tests\MySolution.Tests.fsproj (4.0.0.1 vs 4.2.1), ...

Known workarounds

None at the moment

Related information

I showed here an example with the nuget of YC.PrettyPrinter but I tried many other libraries and it always fails like this.

It detects F# core 4.2.1 immediately after the NUnit.Runners:

Paket version 5.0.0
Adding YC.PrettyPrinter to C:\Repos\ProjectScaffold\paket.dependencies into group Test
Skipping resolver for group Build since it is already up-to-date
Skipping resolver for group Main since it is already up-to-date
Resolving packages for group Test:
 - NUnit 2.6.4
 - NUnit.Runners 2.6.4
 - YC.PrettyPrinter 0.0.5
 - FSharp.Core 4.2.1
 - System.IO 4.3.0
 ...

I'm using this VS:

Microsoft Visual Studio Professional 2017 Version 15.2 (26430.13) Release VisualStudio.15.Release/15.2.0+26430.13 Microsoft .NET Framework Version 4.6.01586

Visual F# 4.1 00369-60000-00001-AA382 Microsoft Visual F# 4.1

NuGet Package Manager 4.2.0