Wrong error message from resolver

Description

redirects: on
source https://nuget.org/api/v2
source https://ci.appveyor.com/nuget/fsharp-formatting

//Build
nuget FAKE >= 4.63.0
nuget FSharp.Compiler.Service >= 13.0.0
nuget FSharp.Compiler.Tools >= 4.1.21
nuget FSharp.Formatting >= 3.0.0-beta06 prerelease
nuget FSharpVSPowerTools.Core
nuget NUnit.Runners ~> 2
nuget Mono.Posix

// Project
nuget FSharp.Core ~> 4.1.0
nuget SimpleInjector
nuget FSharp.Configuration >= 1.2.0
nuget Yaaf.ApplicationInsights
nuget Microsoft.Owin.Host.HttpListener
nuget Microsoft.Owin.Hosting
nuget Mono.Security
nuget Nancy
nuget Nancy.Owin
// Latest has NullReferenceException...
nuget Nancy.Authentication.Forms
nuget Nancy.Validation.DataAnnotations
nuget Nancy.Viewengines.Razor
nuget Novell.Directory.Ldap
nuget FSharp.Interop.Dynamic
nuget Dynamitey
nuget Lucene.Net
nuget Lucene.Net.Contrib
nuget Lucene.Net.Linq
nuget Yaaf.FSharp.Helper
// Not needed in the future.
nuget Yaaf.Database.MySQL
nuget Yaaf.MessageArchiveManager.MySQL


// Test
nuget NUnit
nuget Foq content: none >= 1.7.2
nuget FsUnit
nuget Unquote

github matthid/Yaaf.FSharp.Helper src/test/Test.Yaaf.FSharp.Helper/MyTestClass.fs
github matthid/Yaaf.Xmpp.Runtime:develop src/test/Test.Yaaf.Xmpp.Runtime/TestHelper.fs

yields

$ .paket/paket.exe update
Paket version 5.84.0
Resolving packages for group Main:
 - FSharp.Core 4.1.17
 - NUnit.Runners 2.6.4
 - FSharp.Compiler.Service 13.0.0
 - FAKE 4.63.0
 - FSharp.Compiler.Tools 4.1.23
 - FSharp.Formatting 3.0.0-beta06
 - FSharp.Compiler.Tools 4.1.21
 - NUnit.Runners 2.6.3
 - NUnit.Runners 2.6.2
 - NUnit.Runners 2.6.1
 - NUnit.Runners 2.6.0.12051
 - FSharp.Core 4.1.12
     FSharp.Core 4.1.12 was unlisted
 - FSharp.Core 4.1.2
     FSharp.Core 4.1.2 was unlisted
 - FSharp.Core 4.1.0.2
     FSharp.Core 4.1.0.2 was unlisted
 - FSharp.Core 4.1.0
     FSharp.Core 4.1.0 was unlisted
Performance:
 - Resolver: 3 seconds (1 runs)
    - Runtime: 497 milliseconds
    - Blocked (retrieving package details): 1 second (15 times)
    - Blocked (retrieving package versions): 845 milliseconds (1 times)
    - Not Blocked (retrieving package versions): 76 times
 - Average Request Time: 546 milliseconds
 - Number of Requests: 44
 - Runtime: 6 seconds
Paket failed with
-> There was a version conflict during package resolution.
     Resolved packages:
      - FSharp.Core 4.1.0
      - NUnit.Runners 2.6.0.12051
     Conflict detected:
      - Dependencies file requested package FSharp.Core: >= 4.1 < 4.2
      - FSharp.Compiler.Service 13.0.0 requested package FSharp.Core: >= 4.1.17

     Please try to relax some conditions or resolve the conflict manually (see http://fsprojects.github.io/Paket/nuget-dependencies.html#Use-exactly-this-version-constraint).

Which might be correct from the resolver standpoint but doesn't make a lot of sense from a users perspective...

Important is the info that this conflict holds because of FSharp.Formatting. Here is the nuspec (because it is not released on nuget yet):

<?xml version="1.0" encoding="utf-8"?>
<package xmlns="http://schemas.microsoft.com/packaging/2013/05/nuspec.xsd">
  <metadata>
    <id>FSharp.Formatting</id>
    <version>3.0.0-beta06</version>
    <authors>Tomas Petricek, Oleg Pestov, Anh-Dung Phan, Xiang Zhang, Matthias Dittrich</authors>
    <owners>Tomas Petricek, Oleg Pestov, Anh-Dung Phan, Xiang Zhang, Matthias Dittrich</owners>
    <requireLicenseAcceptance>false</requireLicenseAcceptance>
    <licenseUrl>http://github.com/fsprojects/FSharp.Formatting/blob/master/LICENSE.md</licenseUrl>
    <projectUrl>http://github.com/fsprojects/FSharp.Formatting</projectUrl>
    <iconUrl>https://raw.github.com/fsprojects/FSharp.Formatting/master/docs/files/misc/logo.png</iconUrl>
    <description>The package is a collection of libraries that can be used for literate programming with F# (great for building documentation) and for generating library documentation from inline code comments. The key componments are Markdown parser, tools for formatting F# code snippets, including tool tip type information and a tool for generating documentation from library metadata.</description>
    <summary>A package of libraries for building great F# documentation, samples and blogs</summary>
    <releaseNotes>- Include razor component.</releaseNotes>
    <copyright>Copyright 2014</copyright>
    <tags>F# fsharp formatting markdown code fssnip literate programming</tags>
    <dependencies>
      <dependency id="FSharp.Compiler.Service" version="[12.0.5, 13.0.0)" />
    </dependencies>
  </metadata>
</package>

The error should read:

     Conflict detected:
      - Dependencies file requested package FSharp.Compiler.Service: >= 13
      - FSharp.Formatting 3.0.0-beta06 requested package FSharp.Compiler.Service: >= 12.0.5 < 13

Note that this is unrelated to FSharp.Core. And the conflict paket reported is actually solvable by just using FSharp.Core 4.1.17.

I think this might be related to https://github.com/fsprojects/Paket/issues/2589

Start by tracing the resolver's dependency-conflict reporting using the supplied FSharp.Formatting and FSharp.Compiler.Service example. Compare the reported FSharp.Core conflict with the dependency chain that introduces it, and consider the work done when the error identifies the relevant package and constraints shown in the requested output.