Arvados

Steps to reproduce:

1. Open the sharing dialog on an unshared object.
2. The top pulldown should say "Private."
3. Pull down that menu and select "Shared"

There's a flash, then the dialog reloads and the pulldown is back on "Private".

I realize that "an item shared with nobody" isn't really a meaningful state in the API, but this is confusing and frustrating. Since this pulldown is at the top of the dialog, it seems like the first thing you should change, and Workbench 2 basically just ignores you when you try.