Implicit folder through Finder on Mac

Running macOS 10.12.5

I used an implicit folder as such, before my_friend had set up a keybase account:
/keybase/private/,my_friend@facebook

Once he set up keybase and linked his facebook account, I had to restart Finder before I could successfully run

`open /keybase/private/,`

Before restarting, trying to run
`open /keybase/private/,my_friend@facebook`
threw many pop-up errors.

Reproduce on macOS 10.12.5 with Finder and the documented open commands, first before and then after the friend links a Facebook account. Check whether restarting Finder is required and record whether the implicit path opens or produces pop-up errors; done means the path works without restarting Finder.

Written by the indexing model from the issue text.