Nuget Package upload - changed behaviour

Hello,

After updating from Proget 4.7.11 to 4.7.13 we've noticed change during package upload to Nuget feed. If you tried to upload package with the same version that was already existing on that feed.

It used to return error:

Failed to process request. 'A package with id 'PackageID' and version '0.16.3-beta03' already exists and cannot be modified.'.
The remote server returned an error: (409) Conflict..

But now it asks for credential to elevate permissions:

nuget-3.4.4.exe push "PackageID.0.16.3-beta03.nupkg" apikey -Source api-endpoint )
Pushing PackageID.0.16.3-beta03.nupkg to 'api-endpoint/
Forbidden api-endpoint 19ms
Please provide credentials for: api-endpoint
UserName: Password: Object reference not set to an instance of an object.

Is this desired effect? Can it be toggle off in options?

Product: ProGet
Version: 4.7.13

As far as we can tell, ProGet has never returned a 409 response from that endpoint. A quick Google search reveals this NuGet bug: https://github.com/NuGet/Home/issues/2910

You can fix this by upgrading to NuGet.exe 3.4.5, NuGet.exe 3.5.0-beta2, or a later version.