The beta references this thread as fixing the tab complete, but I'm not seeing a change in behavior.

When there are 2 spaces between foo and bar, and the cursor is between them, it's inserting a 2nd 'bar' text into the editbox line, and the cursor is in the middle of the nick that's been inserted between the bar's

And same thing is happening when the cursor is positioned to follow the comma. Again there's 2 bar's in the editbox, and the cursor is in the middle of the inserted nick.