Players are able to bypass vanish and tell if a vanished player is online by using commands that attempt to autocomplete a user name. Tested in builds 421 and 424

Steps to reproduce

1. Log in as a player with vanish permissions, and vanish
2. Log in as a player without permissions.
3. As the unvanished player, run the command /bal (first few letters of vanished players name). For example, if the vanished player's name is notch, run "/bal not"

Expected results:
The command should return "Error: Player not found."

Actual results:
The command returns the vanished players balance.

Could anyone confirm if this still happens with recent versions that include the tab completion framework?

Unable to reproduce the issue myself, so this should be fixed. Seems like no one else has had this issue for a while either. If someone finds a new vanish / tab completion problem like this, please create a new issue for it.