The original issue appears to be caused by <<smart-indent>> also being bound to Tab, but <<autocomplete>> only being bound using event_add() once in EditorWindow.__init__().  Therefore, RemoveKeybindings() does remove the binding for tab due to <<smart-indent>>, but <<autocomplete>> is not bound again by ApplyKeybindings().

That should mean that tab is still bound to <<autocomplete>> and <<smart-indent>>, as expected, but the order has changed: now <<smart-indent>> was the last event added. We need <<autocomplete>> to fire first.

Specifically, commenting out the line for <<smart-indent>> from config.py causes this bug to no longer happen.