Some more cleanup of CVS keyword noise.

Some more cleanup of CVS keyword noise.

Poking around for remaining occurrences of CVS keyword strings, I came
across one that apparently reflects the use of a $Revision: ...$ string
in the original input data.  Dunno why anybody would be using that in
an MTA's Received: lines, but there it is.  Put it back to the way that
it was originally, according to inspection of the CVS repo.