Remove uncommit on reverting batch input

Currently when the user reverts a batch input, a LogUnit is uncommitted
from the LogBuffer.  It should not be, because the LogUnit containing the
batch input is never committed in the first place (it is only committed
to the LogBuffer when a key is pressed or a new batch input is entered).

Bug: 9088919

Change-Id: I323af453ce082437a663ccae977b21b775a964bc