Please answer some questions before submitting your issue. Thanks!

### Which version of XXL-JOB do you using?

### Expected behavior

### Actual behavior

### Steps to reproduce the behavior

### Other information
使用固定速率，xxl-job宕机重启后，下次执行时间乱掉
This is a GitHub Issue
repo:xxl-job
owner:xuxueli
Title : 使用固定速率，xxl-job宕机重启后，下次执行时间乱掉
Issue date:

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Please answer some questions before submitting your issue. Thanks!

### Which version of XXL-JOB do you using?

### Expected behavior

### Actual behavior

### Steps to reproduce the behavior

### Other information
--- end body ---
