I fixed a similar issue in my solution by:
nuget update -self
This upgraded the copy of NuGet.exe
that was in my solution from 2.8.0
to 3.4.4
, which fixed the 'X' already has a dependency defined for 'Y' error that was stopping it from downloading SSH.NET automatically before building.
(If your solution doesn't have a copy of NuGet.exe
in it - and it might not - then you should try the solution in TN's answer instead)