sql/log.cc:
  a comment for the future.
sql/mysqld.cc:
  if (p) is not needed: fn_ext() always returns a valid pointed; the way
  to test if an extension was found is if (*p), not if (p).
  But here even if there's no extension, we still want to truncate opt_name
  to FN_REFLEN, so we always execute the code.
  By design, the test was always 'false' (because we strip the extension before
  testing if there's an extension) so log->set_no_rotate never executed.
sql/sql_class.h:
  remove set_no_rotate as we don't need it.