slashes.  The old behavior of crossing slashes can be achieved by using a
double-asterisk ('**') anywhere in a pattern.  Note that this can change
some existing exclude patterns in a subtle way.  Also note that if the
remote side is an older release the processing on the two sides might not
be exactly the same when there's no double-asterisk, which can affect which
files are excluded from deletion, but they're close enough that people will
probably not notice.  I considered changing the protocol version and
checking the remote_version number to ensure the same processing on both
sides, but the exclude patterns are pre-processed before the remote version
number is known and it's just not worth going through extraordinary efforts.
Suggested by Cameron Simpson <cs@zip.com.au>