FSharp.Core not mentioned in published Paket lock file

This is related to generation and publication of a lock file to be used with the Paket package manager.

The file was created related to this issue: https://github.com/Azure/azure-functions-host/issues/2446
The file is published here: https://raw.githubusercontent.com/Azure/azure-functions-host/v1.x/src/azurefunctions-v1-paket.lock

The file is not referencing the nuget package `FSharp.Core`. Azure Functions written in F# works when compiled against version 4.0.0.1, and does not work with the latest 4.3.4. Which version is actually used I'm not sure about.