Log Message:
release 3.1:

** Improvements

  grep '[0-9]' is now just as fast as grep '[[:digit:]]' when run
  in a multi-byte locale.  Before, it was several times slower.

** Changes in behavior

  Context no longer excludes selected lines omitted because of -m.
  For example, 'grep "^" -m1 -A1' now outputs the first two input
  lines, not just the first line.  This fixes a glitch that has been
  present since -m was added in grep 2.5.

  The following changes affect only MS-Windows platforms.  First, the
  --binary (-U) option now governs whether binary I/O is used, instead
  of a heuristic that was sometimes incorrect.  Second, the
  --unix-byte-offsets (-u) option now has no effect on MS-Windows too.