R1:1b6eced75706

avoid claiming that the source of a file move was unchanged

Summary:
sometimes we show moved files as unchanged, sometimes deleted,
and sometimes inconsistent with what actually happened at the
destination of the move. Rather than make a false claim,
omit the 'not changed' notice if this is the source of a move.

Background: one of our users was confused by the source of a move
claiming to be unmodified when the destination of the move had
extensive modifications.

There may be a question about the…