Fix for LOGBACK-894 cleanByPeriodOffset add time check

[wuwen5]

Hi @tony19 219

    <p>Fixed <a href="http://jira.qos.ch/browse/LOGBACK-894">LOGBACK-894</a>, 
    <code>cleanByPeriodOffset</code> add time check.
    </p>

[tony19]

Please squash your commits (see rule P5 of CONTRIBUTING.md)

[wuwen5]

@tony19
ok now？

[tony19]

I can't seem to reproduce this error in the existing code. Please provide a unit test. Thanks.

[wuwen5]

@tony19 thanks review.
unit test in TimeBasedRollingWithArchiveRemoval_Test.java

@Test
public void cleanHistoryOnStartWithDayPattern() {
  long now = this.currentTime;
  String fileNamePattern = randomOutputDir + "clean-%d{dd}.txt";     // or %d{HH}
  int maxHistory = 3;
  for (int i = 0; i <= 5; i++) {
    logOncePeriod(now, fileNamePattern, maxHistory);
   now = now + MILLIS_IN_DAY;
  }
  StatusPrinter.print(context);
  check(expectedCountWithoutFolders(maxHistory));
}

[tony19]

This change seems to be causing test failures: https://travis-ci.org/qos-ch/logback/builds/46592291#L2930

@wuwen5, Can you please take a look?

[wuwen5]

@tony19

I Roll back to the previous version for test,and find out 'TimeBasedRollingWithArchiveRemoval_Test.dailyRolloverWithInactivity10' failed at time '23:55'.

[wuwen5]

I do not know why there are 5 minute time difference