I was expecting they would fix the Uri class on Unix (https://github.com/dotnet/corefx/issues/1745) before releasing 1.0 :( Now I fear their backwards compatibility policies will prevent to fix it later. So much for crossplatformness...
They've renamed some packages, so this might possibly be fixed in another one? I found the Ping class didn't work on any non-Windows OS, but it was fixed in a later package with a new name.
Way too many compatibility issues unaddressed by that PR to have a hope of getting anything changed there. Also it looks like what you (?) are trying to do could easily be solved with the Path.* and Directory.* path manipulation functions. No need to put a million apps at risk when you can wrap your call to Uri() with a three line helper.
