Version constraint is missing on referenced projects packed separately #1976

Description

I have a solution that consist of three projects: Two of them are packaged as NuGet packages and one is included in the "top-level" package:

If I add the IncludeReferencedProjects switch to Paket Pack, the version constrain for the shared library is missing.

Repro steps

See provided repo for steps to reproduce: https://github.com/trondd/paket-issue-1976.

Run .\build.cmd to build the solution and create NuGet files. The two outputs in temp should be self-explanatory.

Expected behavior

NuGet dependency should have version constraint.