Created Unassigned: Nuget 2.5.40416.9020 fails to load NuGet.ServerExtensions, Version=2.3.31219.921 [3296]

I would like to enable the [`mirror`](http://docs.nuget.org/docs/reference/command-line-reference#Mirror_Command) command.

Given that I have copied `Nuget.ServerExtensions.dll` to the same directory as `nuget.exe`, when I run `nuget` then I get the following warning.

C:\Users\marijn>nuget
WARNING: Could not load file or assembly 'NuGet.ServerExtensions, Version=2.3.31
219.921, Culture=neutral, PublicKeyToken=null' or one of its dependencies. Opera
tion is not supported. (Exception from HRESULT: 0x80131515)
NuGet Version: 2.5.40416.9020
...

Instead, I'd expect not to get this warning and that the mirror command shows up in the list of available commands.