Paket does not use global nuget cache directory set in configuration file

Description

Using nuget config it's possible to select an alternative nuget cache location: https://docs.microsoft.com/en-us/nuget/consume-packages/configuring-nuget-behavior

However, Paket does not properly use the configured value, causing some strange and confusing error messages, for example:

Package C:\src\project\packages\Microsoft.AspNet.Razor\microsoft.aspnet.razor.4.0.0-beta7.nupkg couldn't be extracted to "C:\src\project\packages\Microsoft.AspNet.Razor". System.IO.InvalidDataException: End of Central Directory record could not be found.. Trying to extract files individually.

Repro steps

1. Set an alternate cache directory: nuget config -set globalPackagesFolder=e:\nuget\packages

2. Verify the configuration: nuget config globalPackagesFolder, should return e:\nuget\packages

3. Use paket restore

Expected behavior

Downloaded packages should be put in e:\nuget\packages

Actual behavior

Downloaded packages end up in C:\Users\user\.nuget\packages

Known workarounds

Setting the environment variable set NUGET_PACKAGES=e:\nuget\packages works.

Start at the Paket restore entry point and trace how NuGet configuration is read, comparing globalPackagesFolder with the NUGET_PACKAGES workaround. Reproduce the issue with the provided nuget config and paket restore steps; done means packages are downloaded to the configured e:\nuget\packages path.