[BUG] [api]Dependent execution fails after task performs serial complement


**To Reproduce**
1.  A task depends on B task, the deviation range is the first 3 days
2. The serial complement of 3 days before the B task execution
3.  Run workflow, dependent execution fails


![image](https://user-images.githubusercontent.com/55787491/69607569-74297400-1060-11ea-9d15-8175e79056ff.png)


**Which version of Dolphin Scheduler:**
 -[1.2.0]


