Hi,
I've seen this error myself occasionally, something a little flaking with the Novell Forge server sometimes, if you keep trying it should resolve itself. I'm able to do a clean checkout from here as of right now.
Be sure and use trunk, branches/2.x is old and is a relic from when we had 2 versions of mojoPortal, one for 1.1 .NET/Mono and one for 2.0 .NET. Since then Mono support has matured and now we only have 1 2.0 .NET version and trunk is the latest stable code of that version. I probably should delete the 2.x branch to avoid confusion.
Thanks,
Joe