Experimental Feature: Include Portable Debug Information.
fennecs originally shipped with windows-only debug info. User dxman reported an issue and warnings with Debugging in Release configuration; and possibly the debug configuration's .pdb files were also not correctly included.
I opted to try a new build with the new .snupkg format to provide accompanying debug information to users of the nuget package, for all types of assemblies.
See also: Creating symbol packages (.snupkg)