Dependencies via project reference are not having versions updated when performing a dotnet pack

[KallDrexx]

Steps to reproduce

1. Go to a directory
2. mkdir test1
3. mkdir test2
4. cd test1
5. dotnet new classlib
6. Edit test1.csproj and add <VersionPrefix>1.0.1</VersionPrefix>
7. dotnet restore then dotnet pack
8. cd ../test2
9. dotnet new classlib
10. vim Class1.cs
11. Change class definition to public class Class1 : test1.Class1
12. Edit test2.csproj and add <VersionPrefix>1.0.0</VersionPrefix>
13. Edit test2.csproj and add:

  <ItemGroup>
    <ProjectReference Include="../test1/test1.csproj" />
  </ItemGroup>

14. dotnet restore then dotnet pack
15. Edit test1.csproj and change version to 1.0.2, then build and repack it
16. go back to test2 folder and update the version to 1.0.1
17. In test2 folder do dotnet restore then dotnet pack
18. Extract the test2.1.0.1.nupkg
19. View the .nuspec file

Expected behavior

Dependency should be listed as:
<dependency id="test1" version="1.0.2" exclude="Build,Analyzers" /> so that any nuget package built against the test2 library auto-restore test1 to 1.0.2

Actual behavior

Dependency is outdated and listed as

<dependency id="test1" version="1.0.1" exclude="Build,Analyzers" />

This is impacting us heavily right now as any time we build a nuget package it has outdated dependencies, which when restored on other projects causes FileLoadExceptions due to dotnet restore restoring an older dll.

Environment data

dotnet --info output:

.NET Command Line Tools (1.0.1)

Product Information:
 Version:            1.0.1
 Commit SHA-1 hash:  005db40cd1

Runtime Environment:
 OS Name:     ubuntu
 OS Version:  16.04
 OS Platform: Linux
 RID:         ubuntu.16.04-x64
 Base Path:   /usr/share/dotnet/sdk/1.0.1

[livarcocc]

Moved this to nuget/home: NuGet/Home#4779.