[general] backup schedule changes

henry (12/01/82)

The schedule of shutdowns for backups has changed a little.  The
Friday backups are now somewhat longer, lasting until perhaps 1915.
There is now no Sunday backup three weeks out of four;  on the fourth
Sunday, there is one lasting the full four hours of the "long" Sunday
backups of the past.  All backups continue to start at 1800 sharp.