Paket failed: String cannot be of zero length (a file has no extension issue again)

[domdom]

Description

Seems to be the same issue as #2405. When running paket install, it fails to remove the nonexistent extension of a LICENCE file contained in a nuget package and fails to install it.

Repro steps

1. Create an empty project

2. Add the following to paket.dependencies

source https://nuget.org/api/v2
nuget Zstandard.Net

3. Run paket install.

Expected behavior

Installs Zstandard.Net

Actual behavior

Fails to install with a paket error:

Paket failed with
-> ArgumentException: String cannot be of zero length.
  Parameter name: oldValue

I've tracked it down to line 59 of InstallModel.fs