Issue #8117: Updated NEWS entry and added to logging documentation.

Doc/library/logging.rst

@@ -1894,6 +1894,11 @@ timed intervals.
    The extensions are date-and-time based, using the strftime format
    ``%Y-%m-%d_%H-%M-%S`` or a leading portion thereof, depending on the
    rollover interval.
+
+   When computing the next rollover time for the first time (when the handler
+   is created), the last modification time of an existing log file, or else
+   the current time, is used to compute when the next rotation will occur.
+
    If the *utc* argument is true, times in UTC will be used; otherwise
    local time is used.
 

Misc/NEWS

@@ -24,7 +24,10 @@ Core and Builtins
 Library
 -------
 
-- Issue #8117: logging: Improved algorithm for computing initial rollover time.
+- Issue #8117: logging: Improved algorithm for computing initial rollover time
+  for TimedRotatingFileHandler by using the modification time of an existing
+  log file to compute the next rollover time. If the log file does not exist,
+  the current time is used as the basis for the computation.
 
 - Issue #6472: The xml.etree package is updated to ElementTree 1.3.  The
   cElementTree module is updated too.